This 9.968-hectare reserve is a water world of swampy bayous. At its heart is Avas Lake, which draws migratory waterfowl in such numbers that their rushing wings may be mistaken for the muffled roar of a distant jet aircraft. The waters also teem with plump, olive-green crocodiles, green fat on the local fish.

In May the lake begins to swell, and vast lagoons from in the basin. Thousands of waterbirds then flock here. In the relatively short dry season many of the lagoons dry out; the lake shrinks, and a large proportion of the waterfowl departs for other climes.

Cano Negro is an angler’s dream, with tarpon the ultimate prize during fishing season. Fishing trips and boat tours leave from the small border town of Los Chiles on the banks of the Rio Frio.