Gwen Stefani on a family vacation in Cabo San Lucas, Mexico on April 2, 2012. Credit: FameFlynet, Inc.

That's one rockin' bikini bod.

Gwen Stefani showed off her figure in Cabo San Lucas Monday, when the No Doubt frontwoman, 42, donned a teeny black bathing suit and a sarong for a family beach outing.

Stefani flew to Mexico to spend time with her hubby Gavin Rossdale, 46, currently on break from his tour with Bush, and their two sons Kingston, 5, and Zuma, 3.

The L.A.M.B. designer has spoken candidly before about her intense workout regime; in 2011 she opened up to the U.K. edition of Elle about her "daily struggle" to stay in shape.

"I work out five days a week," Stefani told the mag. "I can't imagine not doing it."

Her main motivation? The style icon reluctantly admitted it's her love of clothing. "I'd like to have no rules and eat what I want," Stefani said, "but I've learned over the years I'm so disappointed when I can't wear the clothes I want to wear."