At Gran Caverna de Santo Tom_s, one of the longest karst system of Cuba, a part of the cave is exploited since 1994 as show cave. It corresponds to the sixth level (out of the total of seven) of the complex karst system, which lowest part is still active today, being the present course of Arroyo Santo Tom_s. Even with the difficulties related to great distance from the main tourist routes of the island, Gran Caverna de Santo Tom_s was visited in the last 10 years by a significant number of tourists and scientists, due to its remarkable variety of karst landscape, at the surface as well as within the cave, and the important archaeological discoveries therein carried out. Management of the show cave is a good example of low-impact effect of tourism in a karst cave, as many features point out. Among these, the limited number of visitors allowed for each group, the choice in using only wooden ladders and passages to reach the cave entrance, and the adoption of rechargeable electrical light (without realizing any fixed light system in the cave). Gran Caverna de Santo Tom_s, therefore, has a high potentiality for becoming one of the best location in the Caribbean to develop an ecological sustainable tourism and, at the same time, due to its size and length, to allow international and Cuban cavers and scientists to continue carrying out speleological and karst research.