This national sanctuary was established in 1988 and lies on the coast, separate from the other three dry-forest areas. Only about 30 sq km in size, it plays an essential role in conserving Peru’s only region of mangroves. The sanctuary and the surrounding area is one of the few zona-rojas (red zones) left in Peru and it's imperative to check the security situation before heading out. It's best to visit at low tide, when the animals come out to feed.
Agencies in Tumbes also arrange tours for S90 per person (minimum two). including transport. If you want to go it alone, the best way to arrange a visit is through the iPeru office in nearby Aguas Verdes, which can arrange mototaxis and a local guide to meet you at the gate.
Guided mangrove tours are available from Puerto Pizarro as well, though the mangroves here are not technically within the protection of the sanctuary and are not as dense.