While St. Thomas is a modern U.S. territory where credit cards (Visa and Mastercard) are widely accepted at hotels and major retailers, you definitely still need cash for a smooth trip in 2026. The most important reason is taxis: most taxi drivers in St. Thomas do not take credit cards and operate on a cash-only basis with set per-person rates. Additionally, if you plan to visit smaller "mom-and-pop" food shacks, buy souvenirs from local vendors at Market Square, or tip your tour guides and boat captains, cash is essential. It is also a wise backup because the island's internet and power infrastructure can occasionally fail during tropical storms, rendering credit card machines useless. Since the currency is the U.S. Dollar, travelers from the mainland don't have to worry about exchange rates. It is recommended to carry smaller denominations ($1, $5, and $10 bills), as local vendors and taxi drivers often struggle to make change for $50 or $100 bills. ATMs are available, but they often charge high fees if they are outside of a major bank branch.