The easiest way to access the caches is by kayak. You can book a kayak tour from one of the tour operators in the area (Bahia Rica Fishing & Kayak Lodge). Or you can hire one of the local fishermen to take you around by boat. The route is approximately 10 km, so if you opt for kayaking you should schedule at least 4 – 5 hours.
All the caches are close to the water in the public zone. In Costa Rica the first 50 meters from the water is all public.
Make sure to bring water, sunscreen and a hat!
Enjoy!