La Tovara is San Blas's classic excursion: a forty-minute boat ride through mangrove channels and jungle waterways to a freshwater spring where you can swim in surprisingly clear water. Small launches depart from the canal near the bridge into town. The boatmen know the channels well and typically stop to point out wildlife along the way.
The mangrove ecosystem along the route is one of the best preserved on Mexico's Pacific coast. Black-crowned night herons, roseate spoonbills, anhingas, and several heron species are resident; the area falls within one of the most important birding corridors in western Mexico. A small restaurant operates at the spring. The trip costs a few hundred pesos per boat; going early in the morning gives better wildlife viewing and cooler temperatures.