The little beach village of Tenacatita has some of the best and most accessible snorkeling on the Costalegre! Access to the reef is from a little beach down a dirt road leading away from the main restaurant strip in Tenacatita to the right towards the point. It's best to snorkel at high tide, when you'll be able to pass over the reef without scraping your stomach over it!
I saw at least 20 different species of fishes, including an awesome eel and several kinds of puffer-fish. Every time I go back, I see something new!
On the other side of the point, there is also a cool black sand beach, as well as a trail leading to the top of the bluff.
The restaurants in town are cheap and tasty, and you can rent a room from one of the local hotels for 300 pesos, on average, or just pitch your tent under a palapa for 50 pesos a night.