Beach
Pigeon Island Beach
Gros Islet, Saint Lucia · sea 29 °C at its warmest, in September

Sea temperature month by month
Monthly means in °C, NOAA OISST v2.1 climatology 1991–2020.
About
beach in Saint-Lucia
Wikipedia has no article about this beach yet. It is on the atlas from its Wikidata record and its photograph.
Questions
How warm is the sea at Pigeon Island Beach?
The sea off Pigeon Island Beach averages 29 °C at its warmest, in September, and 26.7 °C at its coolest. These are monthly means from NOAA's OISST v2.1 satellite and buoy record for 1991 to 2020, sampled at the beach's own coordinates.
When can you swim at Pigeon Island Beach?
The sea reaches 20 °C or more from All year. Twenty degrees is where most swimmers stop calling water cold; below it, a wetsuit helps.
Where is Pigeon Island Beach?
Pigeon Island Beach is on the coast of Gros Islet, Saint Lucia, at 14.0910, -60.9595. The map on this site flies straight to it.