The 6km-long Manialtepec Lagoon, beginning 14km west of Puerto Escondido along Hwy 200, is an essential spot for bird enthusiasts and a fascinating place for anyone interested in nature. Ibises, roseate spoonbills, parrots, pelicans, falcons, ospreys, herons, kingfishers and several types of hawk and iguana call Manialtepec home for at least part of the year. The best bird-watching months are December to March, and the best time of day is soon after dawn.

　　The lagoon is mainly surrounded by mangroves, but tropical flowers and palms accent the ocean side, and the channel at the west end winds through to a pristine sandbar beach.

　　Several operators run three-hour bird-watching trips in motorized lanchas (outboard boats), with English-speaking guides, binoculars and round-trip transportation from your accommodations in Puerto Escondido. Manialtepec is also a bioluminescent bay where phosphorescent plankton appear for a few nights several times a year. At these times nocturnal boat trips are offered, and you can swim or trail your hand in the water to activate the strange phosphorescent glow. July, August, November and December are often good months for this. Don't bother going when there's a full moon or after heavy rain.

　　From Puerto Escondido, take a taxi colectivo (shared taxi) bound for San José Manialtepec from Av 4 Poniente (M$20 to La Puesta del Sol, 15 minutes), running from about 6am to 8pm, or a Río Grande–bound minibus (M$25) from Av Hidalgo 5, leaving about every 30 minutes from 4am to 9pm.