Corragaun Lough is a small (10ha), shallow (<1m) natural sedimentary lagoon situated on the west Mayo coast, 5 km north of Killary Harbour and 7 km from Killadoon, Co. Mayo. The lagoon lies at the head of a long, shallow tidal inlet impounded by the formation of a dune barrier. Seawater appears to enter on every tide but large volumes of freshwater flow through it at times of heavy rainfall. Salinity probably varies considerably, and measured 25-32psu at the time of sampling (17-19/9/96). Corragaun has changed shape between 1919 and 1976 (Bekkers et al. 1976) and according to local information has been reduced in size considerably over the last 20 years.

Roonah Lough is a large (55ha), shallow (<1m) natural sedimentary lagoon with a cobble barrier and a natural outlet, situated on the west Mayo coast, 10 km north of Killary Harbour and 2 km from Killadoon. The whole coastline from Killary harbour to Roonah Point consists of a complex and dynamic barrier system of dunes and cobbles with lagoons of various sizes and salinities. N.B. The barrier may have been breached since the survey in 1996, and this site may no longer be a lagoon.

Furnace Lough is a large (125ha), deep (up to 21m) oligotrophic natural “rock/peat” lagoon, situated in the northeast corner of Clew Bay, 2 km northwest of Newport. The lake forms the lower part of the Burrishoole valley, separated from the larger Lough Feeagh to the north by a terminal moraine. The two lakes together comprise the Burrishoole Fishery, a fully dedicated research fishery monitored by the Salmon Research Agency of Ireland (Poole 1994). Seawater enters the lake on every tide but the large size of the lake and the volume of water passing through it ensure relatively low salinities at the surface throughout the year, but the lagoon is stratified with a permanent halocline at depth.

A small (2ha ), shallow (<1m) “saltmarsh” lagoon, of an unusual type with a long narrow sluiced tidal inlet leading through a pipe under the road and a very soft bed of  almost liquid marl.  The lagoon is situated 9km northwest of Westport, Co. Mayo, bordering Clew Bay. Salinity probably varies considerably and ranged from 13.4psu in the main body of the lagoon to 30.4psu at the tidal inlet at the time of sampling (15/8/06).

Small (3ha), shallow (<1m) natural sedimentary lagoon with a cobble barrier overlying sand and peat with an artificial pipe through the barrier, situated on the northeast shore of Achill Island, bordering Blacksod Bay, 8km north of Achill Sound. Substratum consists of sand, partly overlying peat, and salinity is probably low most of the time, measuring less than 2psu at the time of sampling (15/8/06).

Situated on the Cloonamore River estuary, 1.5km north of Killala, Co. Mayo. A small (1.5ha) artificial “saltmarsh” lagoon formed behind a coastal embankment with a sluiced inlet. Seawater appears to enter on most, if not all tides. As an “estuarine” lagoon salinity probably varies considerably and ranged from almost fresh (1.4 psu) at the inner most part, up to 32.6 psu near the tidal inlet at the time of sampling (9-10/8/05, 7-8/11/05).