On a private yacht in the French Riviera this weekend, Avril Lavigne and a group of friends once again kicked back with bikinis and designer shades for some fun in the sun.

Not long after the Canadian singer, 26, enjoyed a raucous girls' getaway with their boogie boards, paparazzi on the scene caught one rather surprising guest stepping on board for this weekend's party: Lavigne's ex-husband, Sum 41 rocker Deryck Whibley.

Lavigne, who married Whibley in 2006 and divorced him last year after a yearlong separation, was all smiles as she offered her ex a hello hug on the high seas -- check out photos after the jump.

Conspicuously absent? Lavigne's latest boyfriend, 'The Hills' star Brody Jenner, who was nowhere to be seen on the maritime outing.