I'm guessing that this was at Marineland, a now closed marine life park in Los Angeles.
The LA Zoo never had any tanks with underwater viewing until the current seal exhibit was built a few years ago (and to my knowledge has never had walrus).
It looks like the old Marineland underwater walrus viewing area. One vivid memory I have of standing there and viewing a pair of them back in the 1970s, is of how viciously they were ramming the glass trying to get at me.
