If there's an after-party at the pool for the "Aquaman" world premiere, Amber Heard is prepared.

Heard, who plays DC Comics sea queen Mera in "Aquaman" out Dec. 21, rocked a couture swim cap on London's blue carpet Monday night. The headpiece, covered in green flowers, seemed to be channeling the synchronized water ballerinas of the '50s, which is very on-theme for a movie that has plenty of under-water scenes (based on its trailer footage).

The actress' cap matched her plunging gold and green Valentino dress (that did not appear to be waterproof). Her long gold necklace and metallic stilettos are also probably best on dry land.

Heard's stylist, Karla Welch, explained the look on Instagram with a picture of the ensemble: "When you’ve waited since July to wear a @maisonvalentinohaute couture masterpiece.and, duh, it’s @aquamanmovie so obviously we went for the swim cap!"

We're looking forward for more oceanic outfits on Heard's "Aquaman" press tour. Some recommendations: Floaties, Aqua Sox and a life vest. Hey, Ezra Miller would wear them!