Isla Chora seems deceptively close to the shore, but the trip over from central Sámara is close to a mile (1.3 kilometers), so keep that in mind if you decide to make the trip.
A few athletic swimmers have managed the crossing, but most go by kayak or hire a fishing boat for transport.
It is a good place to snorkel, take a short hike, or just enjoy the beach, and the view looking back toward Sámara is lovely. William Juárez of Carrillo Tours says that a guided kayak/snorkeling tour costs about $40 per person. One company also offers a romantic couples tour that includes dolphin watching in the area and ends with sparkling wine on the beach at Isla Chora, but that will set you back $300 per couple!
Isla Chora has a bit of a split personality. On the bay side there is a quiet white sand beach and the water is calm. Your most likely sightings here will be hermit crabs and iguanas who have learned that guides bring fruit for their clients. The iguanas will do their best to convince you to share your pineapple.
On the Pacific side things get rocky and the waves are bigger. Rock climbing is NOT recommended. The island is made of a sharp crumbling rock that is very dangerous and many who have tried have required rescue or sustained injury.
It is recommended to visit the refuge at low tide when the crossing is shortest and the beach is wide. Snorkeling is best during the dry season as waters tend to be cloudy after heavy rains.
Attention to tides and weather are important as well, but a good guide will make sure your visit is safe so you can just enjoy. There is no cover so be sure to protect yourself with proper clothing and sunscreen.