Old Providence McBean Lagoon
The Park covers 90 land hectares and 995 marine hectares and includes about a 10% portion of Providencia's corral reef -- the 2nd largest reef in the Caribbean. It also includes the Tres Hermanos and Cangrejo Keys.
The rainy season is from July to December with the rainiest months being October and November.
The park can be reached by flying from San Andrés to Providencia (about a 20 minute flight) or by taking a boat from San Andrés (about 8 hours). [FYI, flights to San Andrés can be taken from Costa Rica, Panamá, or from BOGOTA, CARTAGENA, BARRANQUILLA, MEDELLÍN or CALI.] The great news for you gringos that don't speak Spanish is that the main language of Providencia is English or English Creole. At the park you can snorkel the coral reef, swim or sun bathe on the beach, rent a sea kayak or wind surfboard, or hike a nature trail to the top of Iron Wood Hill.
The park is open every day until 5 pm and the entrance fee is about $8 US for adults and $1.50 US for kids 5-12, under 5 = free. If you plan to stay on the island, there are several hotels, cabins, or hostels where you can stay. Here is a link to a great report on where to stay, where to eat, etc.