Until the mid 1980's, Gorgona Island was Colombia's Alcatraz style high security prison. The prison is now derelict, complete with swinging monkeys and a range of other animal and plant life, and makes for a fascinating visit. Gorgona Island also has a few unspoilt sandy beaches (there's much better beaches elsewhere on the Pacific coast though), and the area is great for nature tours, birdwatching and snorkelling. The whole travel experience is like none other. Gorgona Island is also Colombia's best spot for whale watching - the best months are from July to September, when killer whales, amongst others, are often seen. Gorgona is also great for scuba diving.
Pretty much everything is forbidden on Gorgona Island - you're not even allowed to drink alcohol, and your bags will be searched for it upon arrival.
In terms of visiting Isla Gorgona, you're best off contacting Aviatur, who manage all of Colombia's National Parks. They'll book an all inclusive package that includes flights to nearby Guapi, a two hour boat transfer plus the food and accommodation - there's one very beautiful lodge in which to stay, click here for info. The cost of such brief packages is a rather expensive 1 million pesos per person.