Perhaps the sea lion was merely trying to locate a safe haven, but more likely it swam into the shark-diving cage by mistake.
The accompanying video, uploaded last week to YouTube, shows a sea lion (not a seal, as described) swimming into a metal cage through a wide viewing portal. The mammal then became stuck while trying to exit through the metal bars.
Fortunately, one of the divers inside the cage used his foot to help the pinniped escape.
Unfortunately, at least one large great white shark (seen at the beginning of the footage) was lurking nearby.
The YouTube user, Craig Paisley, did not mention the location of this shark dive.