Named after John D. Pennekamp, a former newspaper editor for the Miami Herald and noted Everglades conservationist, John Pennekamp Coral Reef State Park was developed in 1963 as the United States' first park under the sea. The state park is 25 miles long and 3 miles wide, and it is home to many aquatic plant and animal species, in addition to mangroves and various types of birds.

Visitors can enjoy the park in a number of ways. Water enthusiasts can admire colorful coral reef and the popular Christ of the Deep underwater statue on snorkeling and scuba diving tours, while those who would rather stay dry can sign up for a glass-bottom boat tour. There are also 47 campsites and designated spots for swimming, fishing and picnicking.

Spanning 1.5 million acres of wetland across South Florida, Everglades National Park is a worthwhile daytrip for outdoor enthusiasts visiting Key Largo. There are multiple entrances into the park scattered throughout the Sunshine State; the closest to Key Largo is the Ernest F. Coe Visitor Center in Homestead, which is about a 37-mile drive north.

Upon arriving at Everglades National Park (ideally in your own car, as there is no public transportation and car services have trouble navigating the area), visitors will find the largest subtropical wilderness in America. Manatees, crocodiles, alligators, Florida panthers and other wildlife all call the park home, as do a variety of plant species and diverse ecosystems. Outdoor activities abound for visitors of all ages, including biking and hiking trails, bird-watching, kayaking, camping, fishing and many ranger-led tours and programs. Past visitors were especially fond of the nearly mile-long Anhinga Trail and the tram tour through Shark Valley, and many others were floored by how easy it was to spot alligators and other wildlife throughout the park.

Most of Key Largo's dive sites exist within the Florida Keys National Marine Sanctuary, a protected area covering 2,900 square nautical miles. Developed in 1990 to protect precious coral reefs and other aquatic wildlife, the sanctuary is a joint venture between the National Oceanic and Atmospheric Administration and the state of Florida. Popular dive sites off the coast of Key Largo include Grecian Rocks, French Reef and Molasses Reef, and divers will also find several nearby shipwrecks to explore.

Recent travelers who took dive trips within the Florida Keys National Marine Sanctuary had nothing but good things to say. Molasses Reef was deemed a great spot for snorkeling due to its shallow waters, while Grecian Rocks earned praise for its clear waters and abundance of fish.

The Florida Keys Wild Bird Rehabilitation Center is located a short 7-mile drive southwest of Key Largo in Tavernier, Florida. It consists of two facilities: an animal hospital where wounded birds are rehabilitated, and the Laura Quinn Wild Bird Sanctuary, which houses more than 90 birds (across 40 species) that cannot be released back into the wild due to sustained injuries. The sanctuary prides itself on providing humane, natural enclosures where the birds can live out the rest of their lives comfortably. Visitors can embark on a self-guided tour through the habitat to see hawks, owls, pelicans, vultures, herons and more. (Note: The animal hospital section of the center is not open to the public unless you are dropping off an injured bird.)

Recent travelers praised the friendly and informative staff, diverse bird population, live feedings and sunset views on the property. The Laura Quinn Wild Bird Sanctuary is open 365 days a year between sunrise and sunset. Admission is free, though the rehabilitation center does suggest a donation of $10 per person to keep the facility's mission running smoothly. To learn more, visit the Florida Keys Wild Bird Rehabilitation Center's website. 

At Dagny Johnson Key Largo Hammock Botanical State Park, visitors can traverse more than 6 miles of accessible nature trails by bicycle or on foot. The park was named for Dagny Johnson, a local environmental activist. It's also home to one of the country's largest tracts of West Indian tropical hardwood hammock. The park features 84 protected plant and animal species, including flora like mahogany mistletoe and fauna like the American crocodile. For added convenience, visitors will find a picnic pavilion, as well as on-site restrooms. Most of the trails are paved, making them accessible to wheelchair users.

Recent travelers said the park is a relaxing place to stop and explore for a bit, noting that the park's relatively small size and paved trails were easy to manage for visitors of all ages. However, they stressed to load up on bug spray to combat the droves of mosquitos – especially during the summer.

Built in 1912, this iconic steamboat's claim to fame is its role in the 1951 film, "The African Queen," starring Humphrey Bogart and Katharine Hepburn. The vessel has a storied history that spans more than a century and several continents, but it has resided in Key Largo since 1982. The African Queen underwent a $70,000 restoration in time for its 2012 centennial, and today it offers 90-minute dinner outings (with a stop at a waterfront restaurant) and canal cruise tours to patrons at 10 a.m., noon, 2, 4 and 6 p.m. daily.

Recent passengers offered mostly positive reviews and praised the knowledgeable, enthusiastic tour guides and relaxing ride through the canals. However, past travelers noted that an interest in the movie is a must, otherwise you may find the experience a bit dull.

In June 2002, a retired Navy ship called the USS Spiegel Grove was intentionally sunk 6 miles off the coast of Key Largo to support the underwater ecosystem as a manmade reef. The 510-foot vessel is one of the largest ships ever to be sunk for that purpose, and it attracted fish and other marine life right away.

Fast forward to present day, and the wreck serves not only the environment, but also the diving community. It is a favorite dive spot among many recent reviewers thanks to its unique features and abundance of colorful fish. However, because of the massive size and positioning of this artificial reef (the ship resettled nose-up in 2005 after Hurricane Dennis, with its deepest spot at 130 feet), instructors recommend that only experienced divers take on Spiegel Grove. In fact, some areas of the ship are considered too dangerous even for those with high-level certifications.