San Pedro La Laguna has some of the best lake access on Atitlán for swimming. The town has two docks — one to the east (the main lancha dock) and one to the west — and swimming off the rocky shoreline between them is a daily ritual for long-stay travellers. The water is clean, clear, and cold at around 18°C year-round; the altitude means it never warms up regardless of the season.
Several guesthouses right on the waterfront have small platforms or docks from which you can swim. The best spots for a private swim are the rocky inlets to the west of the main dock, reachable on foot in ten minutes from the town centre. Swimming in the early morning, when the lake is glassy calm and the volcanoes are reflected in the water, is as good as it gets.