Kim Kardashian Celebrates North's 12th Birthday on a Sweet Yacht

Kim Kardashian is in full vacation mode with North West ... as mom and daughter hit the waters off Mexico in a fancy yacht to celebrate NW's birthday.

TMZ just obtained photos of Kim and North enjoying some fun in the sun this Father's Day as they cruised around in their boat in Los Cabos, Mexico.

The reality star seemed super chill in her sexy outfit, topped off with a pair of black shades. At various points, Kim is seen holding her phone, a fruit drink, and a binder with pages inside.

The binder's kinda interesting ... Maybe Kim's brushing up on some statutes to take the bar exam again after recently graduating law school.

As for North ... she turned 12 on Sunday -- so her little boat ride with her famous mom must have been part of her celebration.

Gotta say ... pretty cool way for North to spend her birthday, which was also attended by her friends and even her cousin Penelope Disick -- the daughter of Scott Disick and Kourtney Kardashian.

In case you're wondering ... the rest of the Kardashian clan was not seen on camera ... but that doesn't mean they weren't somewhere on the boat. Of course, North's dad, Kanye West, wasn't present given his acrimonious relationship with Kim.