A boat trip through the jungle to the freshwater spring of La Tovara - a federally protected estuary - is a real San Blas highlight. Small boats go from the embarcadero (jetty). The three-hour trips go up Estuario San Cristóbal to the spring, passing thick jungle and mangroves. Bring your swimsuit to swim at La Tovara; there's a restaurant there, too.

For a few pesos more you can extend the trip from La Tovara to the Cocodrilario (crocodile nursery), where toothy reptiles are reared in captivity for later release in the wild. For a group of up to four people it costs around $360 to go to La Tovara (3½ hours) and around $440 to the Cocodrilario (four hours).