Every so often, someone I know is going to St Thomas or one of the other Virgin Islands, and I find myself answering the same questions. Eventually I realized I should just post something here.
The Virgin Islands are breathtakingly gorgeous. If you've never been to the Caribbean before, you're in for a real treat. Even if you have been to the Caribbean before, you're still in for a real treat.
Beaches: There are many excellent beaches on St Thomas.
On the north side, Magens Bay is a long and well-protected beach with fine sand, a decent number of trees that provide some shade, and ample parking. It is my default spot for long-distance swimming, and while it's not particularly known for snorkeling, I always see green sea turtles in the sections with turtle grass. It can get very busy on weekend afternoons and when cruise ships are in port. On the infrequent days when the north side is rough, I head over to Brewers Bay on the south side of the island just past the airport. It's a comparable length to Magens, with more coral and shells on the beach and a greater variety of stuff to see underwater -- be on the lookout for octopuses (octopi? octopodes?). I also like many of the beaches on the east end of the island, in particular, Secret Harbor and Coki for snorkeling or diving, though note that these are much smaller beaches that can get very crowded during the day, especially Coki. I also like Lindquist (aka Smith Bay Park) for the solitude. There are dozens of beaches to choose from, each with something different to offer, and even the same beach can feel completely different at different times of day.If you'll be on St Thomas for more than a couple days, I recommend spending a day on St John, reachable via passenger or car ferry from St Thomas. All of the beaches on St John are spectacular; you can just drive along the north side of the island and overlook and stop at beach at the beach. I enjoy really long swims, so usually end up at some combination of Maho and Francis or Cinnamon. Trunk Bay and Hawksnest are great smaller picturesque beaches with snorkeling. For those who don't mind a bit of a hike, Leinster Bay and Salt Pond Bay are great snorkel spots.
Or get away from the crowds by driving all the way to the east end and snorkeling at Haulover or Hansen Bay.Other water activities: There are many options for spending time on the water, from snorkel and sunset sails, to kayaking and paddleboarding, jetskiing and kiteboarding, or sailing or chartering a boat of your own and island-hopping the surrounding islands. (Note: You must clear customs when crossing between the USVI and BVI.). I spend a lot of time under the water scuba diving. There are half a dozen dive operators on St Thomas and countless sites to explore. If you've never been scuba diving before, you can do a discover scuba dive or take a dive course to get certified. (To save time, you might want to take the online portion of the course in advance and then do your dives while visiting.)
Flora and fauna: In addition to the marine life, you'll probably see iguanas and mongoose (mongooses? mongoose dem?) and many birds. Plants include palms, cactus and other thorny plants, mangos and other tropical fruit trees, and bright flowering plants like flamboyants, ginger thomas, hibiscus, and bougainvillea. For a high concentration of animals and plants, check out Coral World Ocean Park, Phantasea Tropical Botanical Garden, the Magens Bay Arboretum, and/or the National Park on St John.
History: The history of the Virgin Islands was shaped by European colonialism and the enslavement of Africans. After being settled by native peoples, the islands were "discovered" by Columbus in 1493, and then settled by the English, Dutch, French, Danish, other Europeans, and Africans (as enslaved people, not colonizers) from the 1600s onwards. The U.S. purchased the islands from Denmark in 1917. Charlotte Amalie, USVI's capital, is home to Fort Christian, Blackbeard's Castle and The Three Queens, Emancipation Garden, the Historical Trust Museum, and many other historic buildings and landmarks. Just offshore, you may appreciate Hassel Island. St John and St Croix also have many historic sites, including forts, sugar mills, and plantations.
Food and drink: Eating out is expensive, and the grocery store selection is limited and expensive. You can find good local cuisine in a number of places including Gladys' Cafe (in town), Petite Pump Room (Waterfront), Brooks (near Magens Bay), and various food trucks. There are many other restaurants and bars in town, Frenchtown, Red Hook, Yacht Haven, and Havensight, as well as at the hotels. I've compiled a list of many restaurants, with hours and menus. Unlike food, alcoholic drinks are neither limited nor expensive. Nightlife is concentrated in pretty much the same areas as restaurants. I spent many a night as a teenager hanging out at the Greenhouse or Duffy's Love Shack. Rum is the drink of choice, and the islands boast several rums, including Cruzan Rum, Captain Morgan (formerly of Puerto Rico), and Pusser's (BVI), and several drinks, including Mountain Top's banana daiquiris, Sapphire's bushwackers, and Soggy Dollar's painkillers. Another islands institution is Udder Delights (formerly St Thomas Dairies), which is a convenient stop for milkshakes and ice cream to cool off after a day at Magens.
Shopping: I'm not a shopper, but there are shops in downtown Charlotte Amalie, around the cruise ship docks, and in Yacht Haven. You can find the usual assortment of tourist wares, as well as a variety of high-end jewelry and duty-free goods. For a quieter experience and local crafts, try Tillett Gardens on St Thomas or Mongoose Junction in Cruz Bay, St John.
Carnival: For an authentic Caribbean experience, consider visiting during Carnival, a lengthy fete of calypso and soca music, parades, and revelry. (Each of the main islands have their own Carnival at different times of the year.)
St Croix, the largest island, is 42 miles (68km) south of St Thomas. There are airplanes and seaplanes between the islands, as well as a daily ferry (though I hear the crossing can be rough).
History: See Fort Christiansvaern and take a walking tour of the rest of Christiansted. Go to Frederiksted, the other town located on the west end of the island. While there's not much to see there, you may also want to visit Columbus Landing, a site where Columbus may have landed in 1493.
Nature: I like the St George Village Botanical Gardens. I've also heard good things about Estate Whim, but they have erratic hours (likely corresponding with cruise ships) so check before going.
Ocean: As a St Thomian, I'm not especially impressed with the main St Croix beaches of Cane Bay and Cramer Park, but they're still decent beaches. There's also a bit of snorkeling in Frederiksted. Although it's less accessible, Buck Island is a great spot to visit, especially for snorkeling or scuba diving. There are several dive operators that dive Frederiksted Pier, the Wall, and other sites.
From St Thomas and St John, you can take a ferry to the nearest main islands of the BVI: Tortola, Virgin Gorda, and Jost Van Dyke.
Beaches:There are many great beaches in the BVI. You can easily take day trips to the popular The Baths on Virgin Gorda and White Bay on Jost Van Dyke.
Ocean: From St Thomas and St John, you can take daysail and snorkel tours to the Baths and other sites. The BVI also has many excellent dive sites.
Food and drink: The BVI is home to a number of famous bars and restaurants, including Foxy's and Soggy Dollar on Jost Van Dyke, Pusser's and The Sugar Mill on Tortola, and Cooper Island Beach Club.
Old Years': Celebrate the end of the year and ring in the new at Foxy's.
Passport: If you're visiting the BVI, you need a passport (even if you're a U.K. national). If you're visiting the USVI and are not a U.S. citizen or are visiting from somewhere other than the U.S. mainland, you need a passport. If you're a U.S. citizen visiting only the USVI from the U.S. mainland, you will need either a passport or both a government-issued photo ID and a certified birth certificate to return to the U.S. mainland. In short, bring a passport.
Clothing: Bring at least one bathing suit, a beach cover-up (preferably one that will keep your shoulders from burning), and shoes that you don't mind getting sandy or wet. Short-sleeve or sleeveless shirts and shorts (or skirts, dresses, or lightweight pants) will be most comfortable during the day. Bring at least one pair of lightweight pants (or a skirt or dress) for restaurants where shorts will be out of place. Pants also provide some protection against mosquitoes. You may want a light sweater for air-conditioned restaurants, but you're not likely to need one outdoors.
Sun and bug protection: Remember that you can get sunburnt even when it is cloudy. Bring SPF/UPF cover-ups, including ones you can swim, a hat or a visor, and sunglasses. For anything you can't cover, wear sunscreen. Note that oxybenzone, octinoxate, and octocrylene sunscreens are prohibited in the USVI; use zinc oxide or titanium dioxide sunscreens instead, preferably ones that have been tested to be reef safe. There are mosquitoes, especially during the rainy season. Mosquito bites are itchy and mosquitoes can carry diseases. Bring insect repellent that is at least 20% DEET. Aloe and anti-itch remedies are also useful to have.
Other: Bring snorkel and/or scuba gear if you have; if not, there are many convenient rentals.
As places to visit go, the Virgin Islands is pretty close to paradise. But paradise can be deceptive.
Sun and bugs: Welcome to the tropics. It's hot, and it's easy to get sunburnt or dehydrated. Avoid midday sun, stay in the shade, drink lots of water, and wear SPF/UPF clothing and allowed sunscreens. At times local mosquitoes have been known to carry diseases: dengue, chikungunya, and zika. Avoid mosquito bites as much as possible.
Weather: It's sunny and warm all year, with pleasant tradewinds that usually moderate the temperature. That said, it can be pretty hot from May to September. Isolated rainstorms are common and can leave you ducking for cover on the beach. Many rain showers only last a few minutes, and you're often rewarded with a rainbow. Hurricane season (also the rainy season) runs from June through November, with September typically being the most active month. If you're planning a visit then, note that some places may be closed or have limited hours. Also, pay attention to weather forecasts. Hurricanes suck. (Small comfort: as a tourist, if there is a hurricane, you'll be able to get on one of the first planes or ships off-island afterward.)
Driving: We drive on the left-hand side of the road (like in the U.K.) using left-hand drive vehicles (like in the U.S.). Yes, really. Roads are narrow, curvy, steep, and potholed. Sometimes the potholes have potholes. If you're renting a car, drive slowly and keep left. If you're not renting a car, there's an abundance of group taxis and safari buses that will take to you anywhere you're likely to want to go. Taxis won't leave until they are full, so plan accordingly.
Liming: As in most of the Caribbean and Latin America, the pace of life here is slow. We take our relaxing ("liming") seriously and don't care much for schedules and hurrying. Slow down and be patient, and you'll enjoy being on "island time". If you're expecting fast service and planning tight schedules, you're likely to be disappointed.
Be respectful: This is not a theme park. Actual people actually live here. Greet locals with "good morning", "good afternoon", and "good night", and remember your pleases and thank-yous, or don't be surprised if you don't get good service. Seriously; don't say I didn't warn you. Shirts and shoes are required in stores and restaurants.
Utilities: Outside of the large resorts, power and water outages are common. Water comes from rain, and there are occasionally droughts, so you may be asked to conserve water. Cell phone reception (especially AT&T) is generally good, but can be spotty in valleys. You don't have to pay roaming charges on most U.S. cell phone plans, but beware of roaming charges if you pick up a signal from the BVI. (If you do get roaming charges, you can dispute them on your bill. And while you're at it, please ask your provider to improve their coverage.)
Prices: There are plenty of places you can vacation cheaply, but few of them are in the Caribbean. Nearly everything here is imported, so expect to pay more than on the U.S. mainland, especially for food and gas. However, alcohol, cigarettes, and duty-free items are usually much cheaper here than on the mainland. Note that the U.S. Dollar is the official currency in all of the Virgin Islands (USVI and BVI).
Americanization: The USVI are part of the U.S. While there are many geographical and cultural differences, the USVI -- especially the bits you'll see as a tourist -- are a lot like the rest of the U.S. If you're an American worried about being somewhere foreign, there's no need to worry. We have electricity and running water (well, much of the time), fast-food restaurants, and many (well, some) of the chains you are used to. If, on the other hand, you're trying to avoid boatloads of Americans, you may prefer to visit off-season or to spend much of your time on less-touristed islands than St Thomas.
Crime and drugs: St Thomas and St Croix have more crime than you'd expect. Act accordingly. Don't leave valuables in your car or unattended at the beach, and avoid walking alone especially in downtown alleys and at night. Alcohol (legal drinking age 18), marijuana (kinda but kinda-not legal), and other drugs are available in abundance. Be responsible, and if you are going to do anything, then at least have a buddy and don't drive under the influence.
For more travel information, I've compiled a list of visitor websites. Enjoy your trip!