Cold water shock
HERE is a search on this website for stories about drownings or near drownings on Tenerife beaches. There are far too many of them.
People may not realize, or have simply forgetten, that cold water shock can affect people even with water temperature of up to 25º. It’s not just freezing water that is dangerous, and scuba diving specialists say that the Canaries’ water temperature doesn’t get above 24°C (75°F) even in August.
The danger is even more pronounced when people are already hot, as they often are in Tenerife after sunbathing, and they can get into difficulties within five minutes of going in the water. Some have a sensitivity anyway to “cold” water, and this increases with age, which might account for why so many of these fatalities or near fatalities are middle aged or older. Even those who have no such sensitivity as such can induce one by drinking alcohol.
Please have a quick look at THIS site, which is typical of many such professional level web page giving advice on cold water shock. Let’s try to cut the numbers down in Tenerife because this happens year after year.