The reserve’s visitor center, the Centro de Interpretación Uyotot-Ja, or ‘Casa de Agua, ’ is 13km along the road to the town of Jonuta, beside the broad, winding Río Grijalva. Here a 20m-high observation tower overlooks the awesome confluence of the Grijalva, the Usumacinta and a third large river, the San Pedrito – a spot known as Tres Brazos (Three Arms). Guides lead you round a nature trail and displays on the wetlands. Boat trips (two hours, up to seven people M$500) are available into the mangroves, where you should see crocodiles, iguanas, birds and, with luck, howler monkeys. March to May is the best birding season.