To hell with June Gloom, these summer stars are in full BLOOM, puttin' their hard-earned assets on display and hittin' the water in bikinis n' speedos ... some celebs even opting for nothin' but skin!

Sexy stars like Cardi B. got wet and bougie with her black swimsuit on a yacht, Luke Evans was excited to show his followers what he's workin' with down under, and the Hamlin sisters -- Amelia Gray and Delilah Belle -- joined forces in their pink bikinis!