Oasis Visitor Center sits within Big Cypress National Preserve in Ochopee. The main draw here is the boardwalk/deck, with warnings of alligators - we saw none on this visit, but it wasn't really "alligator season". There are also a few picnic tables and a seriously overgrown butterfly garden. The building is staffed by the National Parks Service with people ready to answer any questions you might have about the Preserve. There are a few exhibits in the building as well. It's not exactly a destination, but an informative stop on your way through Big Cypress.
Oasis Visitor Center is open from 9AM to 4:30PM 364 days a year (closed on Christmas).