Unique Islands Americans Can Experience Without a Passport

When it comes to exotic islands, travelers don't often think of the United States. But the truth is that Americans have plenty of passport-free options from the mainland to America's faraway territories. Here are some of the most unique islands you can visit without technically leaving the country.

One of only a few Caribbean islands that Americans can visit without a passport, Puerto Rico is full of one-of-a-kind experiences, from the centuries of history on display in Old San Juan to the abundance of nature and wildlife inside of El Yunque Rainforest. Meanwhile, visitors can immerse themselves in the local culture in lively neighborhoods like Santurce and Pinones or relax on any of the island's spectacular beaches, including the white sand of Flamenco Beach on the tiny island of Culebra.

Located in Micronesia, Guam is actually closer to Australia and Japan than the United States but access is a bit trickier than other islands on this list. "Although U.S. citizens are required to possess a U.S. passport, on a case-by-case basis, photo ID and proof of citizenship may be accepted," VisitGuam.com states. While visitors are no doubt drawn to the island's gorgeous beaches like Ypao Beach Park and favorable climate, the destination's rich history can't be denied. Guam boasts more than 130 sites on the National Register of Historic Places and played an important role in World War II. In addition to Guam's historical attractions, the island's vibrant Chamorro culture helps set it apart. Additionally, visitors won't want to miss the epic views from the lookout tower at Two Lovers Point or the bustling Tumon Bay tourist district where you can shop with no sales tax.

Accessible via ferry rides and charter flights, Washington's San Juan Islands is an often overlooked island destination that's sure to be a hit with outdoor enthusiasts. The region is home to more than 170 named islands but San Juan, Orcas and Lopez are the three major islands. Summertime visitors will be met by comfortable temperatures in the 70s and a lengthy list of things to do, including whale watching, kayaking tours, hiking and biking, fishing and scenic drives, among other activities. After working up an appetite, visitors can treat themselves to mouthwatering seafood at Downriggers and other fantastic restaurants as well as sample local libations from San Juan Island Brewing Co. and nearby wineries and cideries.

Regardless of whether you're into relaxation or exploration, the U.S. Virgin Islands have you covered. The passport-free Caribbean destination is comprised of three main islands-St. Croix, St. John and St. Thomas-each of which is unique. Virgin Islands National Park takes up a majority of St. John and is not to be missed as visitors will discover amazing beaches, historic plantation sites, ancient petroglyphs and mesmerizing coral reefs home to a wide array of marine life.

The Florida Keys certainly stand out, but 70 miles west is where travelers will find some of the most unique islands in America. Dry Tortugas National Park is home to Fort Jefferson but less than 1 percent of the park is located on dry ground as a majority consists of open water. This means that boating, swimming, snorkeling and diving are some of the best ways to experience it. The coral reefs here are among the most dazzling in the world and the park's remote location in the Gulf of Mexico makes it the perfect setting for nighttime stargazing.

This barrier island spans two states, stretching from Maryland into Virginia and is most famous for the wild horses that roam its beaches. Visitors to Assateague Island can extend their stay by making camping reservations well in advance or book a hotel or vacation rental in nearby Ocean City, Maryland or Chincoteague, Virginia. In addition to relaxing on the beach, watching the waves roll in and checking out the horses, visitors can enjoy hiking and biking trails, kayaking and canoeing, fishing, crabbing and shelling.

An exceptional alternative to crowd favorites like the Hamptons, Cape Cod, Martha's Vineyard and Nantucket, Rhode Island's Block Island offers plenty of quintessential New England charm far from it all, including the landmark South East Lighthouse and the pulse-pounding Mohegan Bluffs that will have you thinking you've been transported across the pond. Of course, no island is complete without inviting sandy beaches and a variety of wildlife to watch and admire. Don't worry, Block Island has that too.

Traveling to the Hawaiian Islands will prove slightly more challenging in the time of COVID-19 but picturesque Kauai rejoined the state's Safe Travels Program for trans-pacific travel on April 5, allowing visitors to test out of the state's mandatory 10-day quarantine. The Garden Isle remains an adventure seeker's paradise, offering visitors exceptional hiking trails, stellar beaches, massive waterfalls and a seemingly endless list of activities to be experienced from land, air and sea. Just how versatile is this island? You can tour Jurassic Park filming locations one minute and be playing a round of golf on one of the world's most beautiful courses the next.

This car-free Midwest island is located in Lake Huron between Michigan's Upper and Lower Peninsulas. The extraordinary vacation spot moves at a slower pace but certainly doesn't lack things to see and do. The entire island is a National Historic Landmark and, despite being just a 15-minute ferry ride from the mainland, feels worlds away. Visitors can look forward to dozens of miles of hiking trails at Mackinac Island State Park, romantic horse-drawn carriage rides and the island's world-famous fudge as well as numerous restaurants offering al fresco dining and plenty of cozy hotels, resorts, B&Bs, condos and cottages to choose from.

Maine's Mount Desert Island is the sixth-largest island in the contiguous United States and it's best known as the home of scenic Acadia National Park. Attracting millions of tourists each year, the island offers plenty of natural wonders but also tons of New England charm. Visitors can't miss Bar Harbor, a beautiful coastal town offering endless views, boutique shops and delectable restaurants serving up Maine's famous lobster. The island also boasts no shortage of mountains but Cadillac Mountain is by far the most popular. As the highest point along the North Atlantic seaboard, the mountain is the first place to view the sunrise in America in the autumn and winter months between October 7 through March 6.

California's Catalina Island offers numerous one-of-a-kind experiences, from zip line eco-tours to bison and undersea sub expeditions. Travelers can also tour the iconic Catalina Casino in Avalon or lie back in a rented cabana at the nearby Descanso Beach Club. On the island's other end, visitors will discover the rustic village of Two Harbors, where many Hollywood hits were filmed. This area also offers exceptional hiking, mountain biking, kayaking, snorkeling and some of the best scuba diving in the country.