Start your day with a hearty breakfast in town before the drive, then stretch your legs at Cumberland Island Visitor Center for a short coastal walk among dunes and marshes-keep an eye out for shorebirds and wild horses from a safe distance. Continue south with a relaxing detour to Fort Clinch State Park for a picnic and a brief exploration of the historic fort and seaside trails, arriving in St. Augustine in the late morning ready to check into your hotel and stroll into the Old City without hurry.
After checking into your hotel, wander the waterfront and head to Castillo de San Marcos National Monument to watch the cannon demonstration and take in panoramic views of Matanzas Bay; the fort's coquina walls and living-history rangers make the past feel immediate. Follow that with a leisurely walk down nearby St. George Street, popping into local art galleries and sampling fresh seafood at a sidewalk café before catching sunset colors from the Bridge of Lions.
As twilight falls, take a relaxed dinner cruise from the marina to see the city lights and hear tales of old Florida aboard the St. Augustine Scenic Cruise, then step ashore to explore the lively evening scene. After dinner, wander the moonlit grounds of Flagler College-its Spanish Renaissance architecture is especially atmospheric at night-and finish with a nightcap or gelato on Aviles Street, where intimate galleries and historic buildings create a charming end to your first day.
Fuel up with breakfast at The Floridian Restaurant in St. Augustine before an early southbound run; enjoy a scenic coffee stop and short boardwalk stroll at Gamble Rogers Memorial State Recreation Area to break up the drive and watch for wading birds. Continue along A1A and US-1 with a detour to explore the mangrove-lined trails and interactive exhibits at the Marineland Dolphin Adventure touchpool area, arriving in Key Largo mid-morning ready to check in and head straight for a snorkel session at the famed John Pennekamp Coral Reef State Park to see shallow reefs and colorful marine life.
After checking in, cruise down to Dolphins Plus Bayside for a relaxed encounter or educational talk about local marine rescue efforts, then head to Florida Keys Wild Bird Rehabilitation Center to stroll the shaded boardwalks and see rescued herons, pelicans, and ospreys up close. Finish the afternoon with a sunset paddle or guided eco-tour through the mangroves from Blackwater Sound Kayak Adventures, where glassy water and twisting channels reveal turtles and juvenile fish as the light softens.
Unwind after a day on the water with a sunset dinner at Sundowners, where waterfront seating and fresh catch specials pair perfectly with twilight views over Port Largo. After dinner, take a short drive to Florida Keys Brewing Co. for a local brew and live music, then finish the night with a peaceful stroll along the illuminated boardwalk at Layton's Marina to listen to soft waves and plan tomorrow's trip down the Overseas Highway.
Leave Key Largo after sunrise for a scenic drive down the Overseas Highway, stopping for a coastal walk and birdwatching at Cape Florida State Park before continuing over the famed bridges; pause at Pigeon Key (via pedestrian ramp or guided tram) to explore the tiny island's historic marine railway ruins and shaded picnic spots. Arrive in Key West mid-morning and stretch your legs with a lazy bike ride to Fort Zachary Taylor Historic State Park for snorkeling amid shallow reefs and a relaxed beachside lunch beneath the sea grape trees.
Wander through the historic seaport with a guided tour of The Ernest Hemingway Home and Museum to meet its famously polydactyl cats, then stroll to Mallory Square for artisan stalls and street performers as the afternoon light softens. Follow that with a hands-on culinary stop at Old Town Bakery & Café for Key West specialties, then rent a scooter to explore the quieter residential lanes and colorful conch houses toward South Beach for a mellow late-afternoon swim or shell-hunting along the sand.
As the sky deepens, head to Sunset Pier for cocktails and live music where the sun slips beneath the horizon and the crowd's cheers mark the golden finale; linger on the decking to watch color-shifting clouds and passing schooners. Afterward, book a table at Latitudes on nearby Sunset Key (arrive by short ferry) for a table-side seafood feast under lanterns, then cap the night with a moonlit ghost tour through Old Town that winds past hidden courtyards and tells salt-soaked legends of Key West.