tomboyx | Premium Underwear for All Day Comfort. Fit for You.

Swim Tank

Swim Tank - Main image
$44.25 $59 In stock

Category: swimwear

Reveal an aquatic surprise with our water-activated fabric. When dry, black keeps its secrets hidden. But splash some water on it, and watch as gray jellies emerge.

How It Works

Our innovative color-changing technology responds to water contact. The moment moisture hits the fabric, the previously invisible jellyfish print transforms from black to gray. Once dry, the fabric returns to its sleek, all-black appearance—ready to surprise again and again.

The best companion for a swim? Our Swim Tank, providing sun protection, moisture wicking, and a perfect fit in the water and out. Our Swim Tank is made from recycled Bahia, so it’s super durable and moisture wicking, as well as a sun protectant. This way, it’ll keep up with you no matter what you do!

Sustainability note: We recycle 7 water bottles to make each tank

  • Fits close to body
  • UPF 50
  • Quick drying, super durable, and supersoft
  • Heads up, this tank does not include built-in bra
  • 80% Recycled Polyester; 20% Spandex
  • OEKO-TEX®-certified
  • Inclusive sizing from XS-6X
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When it ships

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Standard Shipping: Handling (business days) 0–1; Transit (business days) 7–15.

Express Shipping: Handling (business days) 0–1; Transit (business days) 7–15.

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Delivery costs

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Standard Shipping · United States: $0.00

Express Shipping · United States: $3.99

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Returning an item

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United States · Return window (days after delivery): 30. Return method: By mail. Return postage: Seller pays.

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Customer Reviews (4.8 / 5 · 5 reviews)

Owen ★★★★★

The water-activated print is such a fun gimmick—I wore it in the pool and the gray jellies showed up perfectly against the black. It dries back to solid dark quickly too, which makes the surprise feel fresh every time.

Evelyn ★★★★★

The moment I finally got it wet at the beach, the gray jellies started showing through the black—such a fun little surprise that made me grin. Fabric dried fast and kept its shape after a full swim, which is all I really need.

Amelia Y. ★★★★★

Got mine wet at the pool this morning and the gray jellies appeared instantly—it’s like wearing a tiny aquarium. The dry black fabric hides them completely, which makes the surprise even better when you dive in.