Cueva Ventana

The name means window cave, and that is the whole of it: a short guided walk through a limestone chamber with bats overhead and Taíno petroglyphs near the entrance leads to an opening in the cliff face that frames the Río Grande de Arecibo valley below, a green bowl of karst hills and farmland. Photographs of people silhouetted in the opening have made it one of the island's most reproduced images. The cave sits in the northern karst belt, the same limestone country that produced the Camuy river caves and the sinkhole that held the Arecibo radio telescope, and the surrounding hills are mogotes, steep round haystacks of eroded limestone.

What you actually see

• The window - the cliff opening framing the valley below.
• The petroglyphs - Taíno carvings near the cave entrance.
• The bat chamber - the dark section walked through on the way.
• The mogote hills - the round limestone haystacks of the karst belt.

When to go

December to April is drier and the trail less slippery. Go early: the site limits numbers and the queue builds through the day, and the light through the window is best in the morning. Closed on some weekdays, so check ahead.

Honest expectations

The walk in is short but steep, muddy and slippery, with a scramble near the end; sandals are refused. Helmets are compulsory and access is guided only. Numbers are capped and the wait at busy times can be an hour or more. Photography at the window is a queue in itself.

Nearby

The Camuy caves and Lago Dos Bocas are close; Arecibo is twenty minutes north.