The ocean gradually eroded the hills with granite centers, exposing them while also dividing them from the mainland.

[2] The park is an important breeding ground for birds such as osprey, blue-footed boobies, parakeets, cormorants, and pelicans.

Marine life that can be found in the waters below include the king angelfish, Pacific sergeant major, Cortez sea chub, giant damselfish, Moorish idol, Cortez rainbow wrasse, giant oceanic manta ray, Mexican goatfish, blacknosed butterflyfish, yellowtail surgeonfish, zebra moray, garden eels, eagle rays, octopuses, lobsters, seahorses, pufferfish, parrotfish, trumpetfish, cornetfish, clownfish, nudibranchs, anemones, and (rarely) sea turtles.

[4] Tourists and locals from Puerto Vallarta commonly visit to swim, dive, snorkel, kayak, and paddleboard.

A rocky 250 metres (820 ft) wall on the western side of the islets allows divers to head deeper into the bay, with two dive sites.