Everglades National Park – Head out and see the alligators! Everglades is known as the Sea of Grass, and you can take an airboat on a guided tour across the swamps to get up close and personal with the Gators! Everglades is located along Hwy 41 11 miles West of Florida Turnpike.
Key West – You can easily organize to be on a day or overnight trip down this way. This is a beautiful region.
Miami Beach Botanical Garden – this garden, including a Japanese Garden based on perfect balance and harmony, is peaceful and beautiful, and the admission is free.
Haulover Beach – ok, this may not necessarily be what you mean by nature... But Haulover beach is Miami's most famous nudist beach! You don't get much more natural than that.
Oleta River State Park – such a beautiful area of pristine mangrove forest, with a butterfly garden, a fishing area and bird watching, definitely a great place to go to escape from the city.
Key Largo Underwater State Park is about an hour's drive from South beach, and you can see the stunning living coral reef.
Big Cypress Natural Preserve – Home to bears, the Florida panther and white-tailed deer.
Cape Florida Lighthouse The oldest structure built in Miami-Dade County, the 95-foot high Cape Florida Lighthouse at the tip of Key Biscayne has been restored to its authentic 1855 condition in Bill Baggs Cape Florida State Park. THe park also offers an award-winning beach, bike paths , an oceanfront and a harborfront cafe and fishing.