The sand, the swim and getting in the water

The beach is compact enough to walk end to end in a few minutes, and the sand is pale and soft underfoot, though small stones and bits of coral mix into the wash line here and there—tender feet will appreciate water shoes for the walk in. The bottom shelves gently over sand, the water clears quickly, and the buoyancy makes lying back and drifting effortless, so children manage the entry easily and unhurried long swimmers get exactly what they want.↗

Two things keep the swim simple. There is no lifeguard, as on almost every beach on the island, so swimmers watch themselves. And because the watersports operation launches jet skis from this same sand, the machines work an area away from the swimmers but it pays to notice where they go in and keep your lane clear of theirs—especially with kids in the water.↗

Snorkeling at Rainbow

Set expectations honestly: Rainbow is a swimming beach with a snorkel option rather than a reef destination. The bottom is mostly sand with modest patches of nearshore reef that are reliably fishy—blue tang, sergeant majors and wrasses among them—and the shallow, calm water makes it a good place for a first-timer or a child learning a mask to build confidence. The reef starts close to shore, and unlike almost everywhere else on St. Croix, you can rent snorkel gear right on the sand the moment you decide you want it.↗↗↗

The island's more serious underwater attractions sit minutes away. The Frederiksted pier to the south, with seahorses and octopus on its calm, clear pilings, and Cane Bay on the north shore, with its true coral reef and famous wall, are where snorkelers graduate to after Rainbow. Wherever you get in, use reef-safe sunscreen.↗↗

Rhythms and the rental desk on the sand

Rhythms, the beach bar and grill that has anchored this sand for around three decades, is the reason a beach day here needs no cooler. It runs the full toes-in-the-sand format: shaded tables a few steps from the water, a bar pouring the island's rums, and a kitchen of shareable starters, tacos, sandwiches, burgers, a kids' menu and a rotating daily special, with the frozen Lime in the Coconut as its signature. The bar also posts a live-music calendar, and on music days the afternoon crowd stays through dark. Practically, the only restrooms and showers at Rainbow belong to Rhythms and are for its customers, so build lunch into the day.↗

The second institution is West End Water Sports, the outfitter that turns Rainbow into the island's one true arrive-with-nothing beach. From racks on the sand it rents chairs, umbrellas, snorkel sets, paddleboards, kayaks and floats, and lends out volleyball, bag toss and giant Jenga at no charge. It also runs jet-ski rentals and guided coastal tours, plus inland ATV tours, so one family can split between water and hills and regroup at the bar. The paddle craft earn their keep in the morning glass, when the lee water is at its flattest—though note that the calmest dawn water arrives before the rental desk opens.↗

Sunset, the nightly event

St. Croix lies long on an east-west axis, so only its western shore watches the sun meet open water, and Rainbow faces that show squarely. The sun drops into the sea directly in front of the bar's tables with no headland or island in the way, and the beach reorganizes around it in the last hour of light—swimmers come out, drinks go out and conversation quiets at the drop. The timing moves with the calendar, earlier in winter and past seven at midsummer. Locals add the lore of the green flash, a brief green rim on the sun the instant it disappears on a sharp, cloudless horizon; the only way to settle the debate is to watch the last sliver and not blink.↗