Beach
Playa Xpu-Ha
Quintana Roo, Mexico · sea 29.4 °C at its warmest, in September

Sea temperature month by month
Monthly means in °C, NOAA OISST v2.1 climatology 1991–2020, sampled 18 km offshore, at the nearest open water cell of a 0.25° grid.
About
beach in Quintana Roo, Mexico
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 Playa Xpu-Ha?
The sea off Playa Xpu-Ha averages 29.4 °C at its warmest, in September, and 26.5 °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 Playa Xpu-Ha?
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 Playa Xpu-Ha?
Playa Xpu-Ha is on the coast of Quintana Roo, Mexico, at 20.4717, -87.2575. The map on this site flies straight to it.