There is a cove twenty minutes from the centre of Sant Antoni that almost nobody walks to, because the path is unmarked and the car park is somewhere else entirely. The water there is calm, shallow at the edge and about four metres out in the middle — the kind of place where you can put your face in and immediately see the bottom.
We walk in together, I hand out mask, snorkel and fins, and we spend an hour and a half in the water. There are posidonia meadows to one side, which is where the fish are: saddled bream, wrasse, the occasional octopus if we are patient near the rocks. I will point out what you are looking at and why the seagrass matters, without turning it into a lecture.
No experience is needed and you do not have to be a strong swimmer — we stay where you can stand if you want to. If you have never used a snorkel, we spend ten minutes in the shallows first until breathing through it stops feeling strange. Come alone or bring the family; I take one guest just as happily as eight.