It's nearly impossible to see where mom ends and baby begins. The pup is small now, but he won't be forever. Sea otters are the heaviest members of the weasel family and the male California sea otters can grow to weigh 65 pounds; Northern sea otters can reach up to 100 pounds. Grow up big and strong, lil pup.
Be sure to also visit the Monterey Bay Aquarium's Tumblr, and watch a video of the mom and pup on the Facebook page.