An Loch Mór is situated in the northwest of Inis Oírr, approximately 1 km west of the harbour. The lake is a small (6.6ha), very deep (approx 25m) natural karst lagoon with limestone cliffs along much of the shoreline. The main body of the lake has a uniform salinity of 5 psu between 1 and 5 m depth with lower salinity water over parts of the surface (0-3 psu). Seawater enters from a tidal pool to the northeast of the lake from which diluted seawater (up to 20ppt) runs into the lake through limestone fissures. Much of the shoreline and substrate of the shallow parts of the lake are limestone pavement and stones.

Port na Cora is a very small (0.5ha) natural karst lagoon with a sedimentary barrier of cobbles, on the north coast of Inis Meain approximately 1.5km north of the village. The lagoon is shallow (<1m) and at the time of sampling (9/9/06) appeared eutrophic with dense growths of Enteromorpha. The bed of the lagoon is limestone bedrock with no obvious connection to the sea. Salinity probably varies considerably and was high on the 9/9/06 (31.2psu) but was recorded as 4-15psu during a brief visit in 1996.

Situated 1.5km south of Kilronan on the largest of the Aran Islands. A very small (0.5ha) “estuarine” karst lagoon, which appears to be flooded by all tides but retains shallow water (<1m). Salinity at the time of sampling (08/08/2006) was high (33psu) but measured 16-34psu when visited briefly in 1998.

Loch Phort Chorrúch is a natural karst lagoon with a long, unbroken cobble barrier on the north coast of Inishmore, 2.5 km west of Kilronan. Seawater enters by percolation through the barrier and presumably through limestone fissures and overtopping the barrier during storms. The lagoon is small (4ha), shallow (1m) and low salinity, measuring 0 – 4.5psu at the time of sampling (19-23/8/98). However, water levels were exceptionally high during the sampling period due to heavy rainfall the previous day and salinity may be higher under normal circumstances.

Loch an Chara is a small (4ha), shallow (<1m) karst lagoon with an artificial sluiced inlet, situated on the north coast of Inishmore, approximately 1 km north of Kilronan. The lagoon appears to receive seawater from an underground fissure in the limestone bedrock at the north end of the lake and from a leaking sluice at the south end. According to Robinson (1986) the lake was open to the sea until the last century when land reclamation resulted in the present situation. Salinity ranged from 6 to 20psu at the time of sampling (20-22/8/98).

Situated on the northwest coast of Inishmore, 2.5km northwest of  the town of Kilmurvy (Cill Mhuirbhigh). A small (4ha), shallow (<2m) natural karst lagoon with a cobble barrier. The bed of the lagoon is mostly limestone pavement and stones, with soft mud in the centre and cobbles along the barrier. Seawater presumably percolates through the cobble barrier but also through limestone fissures. Salinity is close to that of seawater and measured 33.5psu at the time of sampling (8/8/2006).

Rincarna Pools comprise two small (0.5ha) natural karst lagoons with a sedimentary cobble/shingle barrier, situated 2.5km northwest of Ballinderreen, Co. Galway on a peninsula on the southeast shore of Galway Bay. Both pools were highly saline, measuring 34.6 (pool 1) and 39.7psu (pool 2) at the time of sampling (22/7/06) and appear to suffer from eutrophication, possibly due to natural accumulations of marine algae.

Bridge Lough is a small (3ha), shallow (<1m), partly artificial  karst lagoon situated on the south side of Galway Bay, 10 km west of Kinvarra, County Clare. The lake is impounded by a causeway which allows a limited tidal exchange through a small outlet. Restriction of tidal flushing through construction of the causeway with such a small outlet appears to have resulted in colmatisation and a concentration of nutrients. The lagoon is privately owned and it was not possible to carry out the more intensive survey of aquatic fauna due to objections from a landowner.

Doorus Lakes are a group of small karst lakes situated 2km northwest of Kinvarra, Co. Galway. Three of these, L. Fadda, L. Namona and a small un-named pool are brackish and regarded as lagoons. All others in the area are believed to be freshwater and were not surveyed. However, this is a difficult area to survey due to undulating topography and difficult access across small fields with high overgrown stone walls, and other lagoons may have been overlooked.

Mweeloon Pools are two small (0.5ha) natural “saltmarsh” lagoons, situated 9km southwest of Oranmore, Co. Galway, on a peninsula at the eastern end of Galway Bay. The lagoons are shallow (<1m) and separated by the main road running east to Tawin. Salinity at the time of sampling (17-18/10/06) measured 29.7psu in both lagoons.

Ardfry Oyster Pond is a small (0.5ha), shallow (<1ha) artificial “estuarine” lagoon, 5km southwest of Oranmore, Co. Galway, on a peninsula leading to Ardfry Point, on the eastern shore of Galway Bay. The pond was presumably created for the cultivation of Oysters and is formed in a small bay with a sluiced inlet. Salinity is presumably generally high and measured 23.6psu on 17/10/06, after a period of heavy rainfall.

Turreen Lough is a small (3ha), shallow (<1m) natural “saltmarsh lagoon” with an artificial sluiced inlet, situated 2.5km southwest of Oranmore, Co. Galway on the south side of Oranmore Bay. Salinity probably varies considerably but measured 12.5-16.7psu at the time of sampling (14/10/06).

Lough Atalia is a large (50ha) “estuarine” lagoon, on the east side of Galway City. It appears to be entirely natural with a shallow sill at the inlet and approximately 80% of the area remains inundated at low tide. Being “estuarine”, salinity probably varies considerably, and measured from 13.4 to 28.3 when sampled in 2006. The lagoon appears to be heavily impacted by industrial and domestic effluents from the city and large areas consist of bare anoxic mud. N.B. A small lagoon referred to as Renmore L. is an extension of L. Atalia in the southeast, and was not surveyed due to problems of access through an Army Barracks.

Lettermullen Pool is a very small (<0.5ha) rock lagoon on the western shore of Lettermullen Island in western Connemara. Six islands have to be crossed by bridges and causeways to reach Lettermullen. Golam Head is the final island in this group which lies 500 metres west of Lettermullen. The pool is usually regarded as a large rock pool into which a freshwater spring runs and seawater enters on spring tides and during storms. It can just as easily be regarded as a small coastal lagoon with a rock barrier. Salinity is generally high, even hypersaline, and measured 34-37psu at the time of sampling in September 1996.

Loch Fhada upper pools are two of a group of lagoons (including L. Fhada itself and L. an Ghadaí), approximately 1 km east of Bealadangan which were included previously as part of the Lough Fhada complex Seawater enters these pools occasionally from high tides flooding through saltmarsh channels in the northwest which flows to the northeast into Loch Fhada then into Loch an Aibhnín. It is possible that seawater also enters the pools from Loch Fhada. The western pool (Sta 1) is very small (<0.5ha), approx. 3m deep, largely stagnant with a salinity of 12.4-29.5 psu., the eastern pool (Sta 2) is slightly larger (0.5ha) but shallower, more like a saltmarsh pool, with a salinity of 18-31.5psu during the sampling period.

Loch an Ghadaí is one of a group of lagoons, approximately 1 km east of Bealadangan which includes L. Fhada upper pools and Loch Fhada, which were included previously as part of the Lough Fhada complex. Seawater enters these pools occasionally from high tides flooding through saltmarsh channels in the northwest which flows to the northeast into Loch Fhada, then into Loch an Aibhnín. It is possible that seawater also enters from Loch Fhada on flood tides. This is the lowest salinity lagoon of the group, measuring 2.9-3.3psu at the time of sampling, but 6-10psu in June 1998 and probably gets considerably higher at times. The lagoon is shallow (mostly <1m) with a bed of granite and coarse sand with luxuriant growths of Ruppia, Chaetomorpha and Lamprothamnium.

Loch Fhada is one of a group of lagoons approximately 1 km east of Bealadangan, which were included previously as part of the Lough Fhada complex. Seawater enters these lagoons occasionally from high tides flooding through saltmarsh channels in the northwest which then flows into Loch an Aibhnín. It is possible that seawater also enters the pools from Loch an Aibhnín on flood tides. Loch Fhada is a small (10ha) rock/peat lagoon.  Depth is up to 7m and the water was stratified at the time of sampling with a noticeable halocline at 3m and a salinity and temperature gradient below this depth. In one area, lower salinity water (15.5psu) was recorded at 5m depth, as if diluted by an underground spring of freshwater.

Loch Tanaí is situated in western Connemara, 5 km north of Costelloe and 6 km south of Camus. The lagoon is a medium sized (12ha), shallow (1m) and lies in an area of lowland peat, connected to Loch an Aibhnín (Section 4.58) by a narrow channel. A good example of a type of lagoon, rare in a European context, but characteristic of parts of the west coast of Ireland, especially in Connemara, referred to as rock/peat lagoons with restricted tidal influence due to the presence of a “barrier” of bedrock and peat.  Salinity probably varies considerably, and ranged from 11-34psu at the time of sampling (22-24/8/96). Very little appears to be known about any aspect of the functioning of brackish lagoons situated in acid peat bogs.

Loch an Aibhnín is a large (55 ha), natural rock/peat lagoon on the south side of Camus Bay, 2 km to the northwest of Bealadangan. Seawater enters through narrow rapids from Camus Bay on spring tides and the lagoon receives diluted seawater from L. Fhada (Code No. IL056) and from L. Tanaí  (Code No. IL057), and freshwater from a number of small streams and long-term seepage from surrounding peatland. The lagoon is uniformly shallow (c2m) apart from a deeper area near the outlet (3-4 m) and average salinity was 18psu on the surface and 25 psu at 1m depth. Substrate is mostly peat, granite rocks and coarse sand and gravel with dense beds of Ruppia and Zostera where substrate allows. The lagoon is bordered by peat bog, granite rocks and bedrock and rough pasture.

Loch Cara Fionnla is a medium sized (13.5ha), shallow (1-2m) natural rock/peat lagoon which drains into the south side of Camus Bay, through a long channel which runs through Kinvarra saltmarsh. At the time of sampling salinity was low, measuring 1.1 –3.5 psu but 24psu was recorded in May 1997. Substrate is mostly granite rocks, coarse sand and gravel with peaty silts in sheltered areas. The lake is bordered by moorland, peat bog and granite rocks.

Cara na gCaorach is not named on the 1;50,000 OS map, but is the name used by Robinson (1997?) for a large (30ha), mostly shallow (1-2m) natural rock/peat lagoon 2.5km south of Kinvarra, Co. Galway, which drains into the south side of Camus Bay, through a long channel which runs through Kinvarra saltmarsh. Salinity probably varies considerably and ranged from 0.9-13.9 psu but 24psu at the time of sampling (15-16/10/06). Substrate is mostly soft peaty silts with outcrops of granite bedrock and rocks. The lagoon is bordered by moorland, peat bog and granite rocks.

A very small (1ha), relatively shallow (3m) natural “saltmarsh” lagoon, situated on the northern shore of Camus Bay, 15km northeast of Kilkieran, Co. Galway. Ranging in salinity at the time of sampling (10/08/2002) from 20-25psu.

Loch an tSaile is one a series of lakes with a natural outlet, at the north end of Camus Bay, 1.5 km west of Screeb. There are three large connected lakes with several smaller embayments which almost form separate lakes in themselves. The two lower lakes are regarded as rock/peat lagoons and together these cover an area of approximately 90ha. Seawater enters from the south on all tides but the lakes also receive large volumes of freshwater from a large catchment area. The lower lake is relatively shallow (0-4m) and brackish throughout while the middle lake is deep (13m) and permanently stratified with water below 3m measuring 14psu.

Lough Aconeera is a moderate sized (26ha) lagoon up to 5m deep in the central parts, situated on the northern shore of Kilkieran Bay, western Connemara, 6 km north of Kilkieran. It is a type of lagoon, rare in a European context, but characteristic of parts of the west coast of Ireland, especially in Connemara, which are permanent and brackish, with restricted tidal influence due to the presence of a “barrier” of granite rocks and peat referred to as a “rock/peat” lagoon. This lagoon lies at the base of a mountain range, Cnoc Mordáin, which rises to 354 m within 1 km of the lake.

Mill Lough is a small (6ha), mostly shallow (1-2m), but up to 4-5m at the southern end, “rock/peat” lagoon, with a natural bridged outlet, situated in the north of Ard Bay, western Connemara, 4 km west of Carna. Mill Lough is included as a good example of a type of lagoon, similar to the Scottish “obs”, which are characteristic of parts of the west coast of Ireland, especially in Connemara. They are permanent, shallow and brackish, with restricted tidal influence due to the presence of a “barrier” of peat, and in this case rock. Seawater appears to enter on all tides, but large amounts of freshwater also enter. Salinity probably varies considerably both spatially and temporally, and ranged from 6-31psu at the time of sampling (27-29/9/96).

A small (2ha), shallow (<1m) “saltmarsh” lagoon, situated 1km south of Carna, Co. Galway, north of the road to Mweenish Island. The bed of the lagoon is mostly bare mud and salinity is generally high and measured 31psu at the time of sampling (7/10/06).

Lough Keeraun is a small (2ha), “rock/peat” lagoon, with a stream running through it, from an “upper” freshwater lake. It is situated in the northern part of Mweenish Bay, 0.5 km south of Carna. Seawater enters from the south, only occasionally and salinity is probably low most of the time, and measured 6.5-7.4psu at the time of sampling (7/10/06), but water flowing from the lagoon measured 8.6psu, suggesting more saline water may remain at depth in central areas which were not surveyed. Underwater observations should be made in this lagoon.

Ballyconneely is a moderate sized (20ha), very shallow (0.5m) natural sedimentary lagoon, with an artificial sluiced outlet running under the road into Ballyconneely Bay. Situated 10km northwest of Roundstone, Co. Galway, and 0.5km southeast of Ballyconneely. It is a “borderline” lagoon. Salinity is probably extremely low most of the time, and measured <1psu at the time of sampling (16-17/7/02). In dry summers it almost dries out completely and is perhaps more of a “machair lake” than a lagoon but remains on the lagoon list for the time being.

Lough Athola is a moderate sized (11ha), mostly shallow (2m) natural rock/peat lagoon, situated on the north shore of Mannin Bay, 3.5km from Ballinaboy, Co. Galway. Sea water enters the lagoon on most tides and salinity measured 33-34psu in most parts of the lagoon at the time of sampling in 1998 (25-26/9/98), but was 27-33psu at one time in 1997 and as low as 6psu in a small bay at the western end.

Lough Anillaun is a moderate sized (15ha), natural sedimentary lagoon with a cobble barrier and a bridged outlet carrying a road, situated 1km east of Cleggan at the east end of Cleggan Bay, 7km northwest of Clifden, Co. Galway. Salinity appears to be very low most of the time due to the large volume of freshwater running through it, and measured 0-11.1 psu at the time of sampling (7-8/8/02), but it is suspected that large volumes of seawater enter occasionally.

Lough Bofin is a small (8ha), shallow (<1.5m) natural sedimentary lagoon with a cobble barrier. The lagoon is situated on the north shore of the island of Inishbofin, approximately 2km to the west of the harbour. The barrier is high and seawater enters the lagoon by percolation and by overwash during storms. Although there is no direct connection with the sea, the volume of the lagoon is small and the amount of seawater that enters, either by percolation or overwashing can be relatively high. Large amounts of freshwater can also enter at times of high rainfall and it appears that the lagoon undergoes extreme variations in salinity. Salinity measured 13-17psu during the sampling period (5-7/8/98), but 32.3-33.1psu was recorded in August 1995.