Bat Islands

The Islas Murcielago lie off the northwestern tip of Guanacaste within Santa Rosa national park, part of the Area de Conservacion Guanacaste inscribed as World Heritage, and they are dived rather than landed on. The site that draws people is Big Scare, a pinnacle where bull sharks gather in numbers and can be seen at close range in the blue, along with rays, turtles and large schooling fish; it is an advanced dive with current, depth and cold thermoclines, and operators require experience. The crossing from the Papagayo area takes an hour or more in open water. Manta rays and whale sharks pass seasonally. The islands themselves are dry rock and scrub with seabird colonies.

What you'll find

• Bull sharks - the aggregation at the Big Scare pinnacle.
• Rays and turtles - the other large animals on the sites.
• The rock islands - the dry scrub-covered islets and their seabirds.
• The crossing - the open-water run from the Papagayo coast.

When to go

May to November is the better window for shark numbers and warmer water; the dry season brings clearer conditions but cooler thermoclines and stronger winds. Trips cancel in rough seas.

What to expect

This is an advanced dive with current, depth and cold water, and operators require logged experience. The crossing is long and often rough. Shark sightings are not guaranteed. Landing on the islands is not part of the trip.

Nearby

Playas del Coco lies south; Santa Rosa national park is on the mainland.

Key facts