Kendall Jenner and Hailey Bieber are doing what models do best in the summer.

The bikini-clad besties were photographed enjoying a yacht day in Cabo San Lucas, Mexico, with two of their equally beautiful girlfriends: Lori Harvey and Justine Skye.

For the lavish yet relaxing outing, the group wore tiny swimsuits, soaked up the sun, took dips in the crystal-clear water, rinsed off at the onboard shower station and sipped on Jenner’s 818 Tequila.

Jenner, 27, rocked a slinky, snakeskin two-piece with small hoop earrings and black sunglasses, later modeling a cowboy hat.

With a bottle of her liquor in hand, the “Kardashians” star smiled as she poured shots for her pals – and even directly from the bottle into their mouths.

Bieber, 26, stunned in a bright blue string bikini with white accents, completing her seaside look with small hoop earrings and a statement necklace featuring the letter B.

At one point, she also sported a daisy-printed bucket hat.

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The very tan wife of pop star Justin Bieber was snapped happily throwing back a shot of tequila as Harvey, 26, looked on.

The daughter of famed TV host Steve Harvey sported an orange crisscross bathing suit top and white bottoms – perhaps from her newly launched line, Yevrah – and finished off her look with chic shades, small hoop earrings and her hair styled in braids.

Meanwhile, Skye opted for a flower-patterned bralette-style top and matching high-waisted bottoms, which she paired with a blue headband and stud earrings.

The songstress celebrated her 28th birthday aboard the luxury boat, as social media photos show her posing in front of a decorated cake topped with a massive, sparkling candle.

The fabulous foursome made sure to document their boujee afternoon with various photo shoots captured by their respective cellphones.