The park's defining feature is its lagoon system: Laguna de Chacahua, Laguna de La Pastoria, Laguna Las Salinas, and a constellation of smaller bodies connected by narrow channels that wind through dense mangrove forests. Roughly 30 of the park's total area is water, and the boundary between land and lagoon shifts with the seasons. The rainy months from June through November swell the channels and push saltwater into freshwater zones, creating a dynamic mosaic of habitats. Ten distinct vegetation types have been documented within the park boundaries - selva espinosa, swampland, deciduous forest, subtropical broadleaf, mangroves, savannah, bosque de galleria, tular, palm groves, and coastal dunes. Researchers have cataloged 246 plant species and 189 animal species, though those numbers almost certainly undercount a landscape this varied. Storks, herons, wild ducks, blue-winged teals, pelicans, and roseate spoonbills wade through the shallows, while three species of sea turtles return each year to nest on the park's beaches.

Getting to Chacahua is itself an experience worth having. From El Zapotalito, travelers choose between a short lagoon crossing followed by a pickup truck ride along a dirt road, or a longer direct boat trip that threads through the mangrove channels. The longer route functions as an unguided wildlife tour - egrets perch in the branches overhead, fish break the surface, and if the light is right and the water is calm, you might spot a crocodile's eyes and nostrils hovering just above the waterline. The mangrove channels narrow in places to little more than the boat's width, branches forming a green tunnel that opens suddenly onto broad lagoon expanses where the sky doubles itself on the still water. It is the kind of approach that recalibrates expectations. By the time you step onto the sand at Chacahua, the urgency of wherever you came from has been thoroughly rinsed away.

Chacahua's surf breaks form around a stone jetty, producing long right-hand waves that build in summer and attract a growing but still manageable crowd of surfers - nothing like the packed lineups at nearby Puerto Escondido. But the park's most otherworldly attraction requires darkness. On moonless nights, the lagoon water lights up with bioluminescence - microorganisms that emit blue-green light when disturbed by a hand, a paddle, or a swimming body. Tours leave after sunset, and the effect is genuinely astonishing: every movement trails phosphorescent fire through black water. The darker the night, the more vivid the display. On the opposite shore of the lagoon, a short hike leads to a lighthouse that offers sunset views worth the mosquito bites required to earn them. Bring repellent, something to drink, and a willingness to sit still while the Pacific turns orange and then violet across a horizon unbroken by any structure taller than a palm tree.

Chacahua the village operates on a rhythm that has little to do with clocks. Almost everything is located directly on the beach, and walking is the only way to get around. The restaurants serve fresh-caught fish alongside Oaxacan staples - tlayudas, tacos - and the occasional pizza or burger for visitors craving something familiar. Rooms rent cheaply along the beachfront, and prices drop further for anyone staying more than a day or two. Some places offer hammocks or camping spots, and at least a few will let you pitch a tent for free if you eat at their restaurant once a day. The arrangement is simple, informal, and built on the understanding that everyone in Chacahua is there for roughly the same reasons: the waves, the lagoon, the unhurried pace of a place where the loudest sound at midday is usually the surf.