How do they put the glass in at SeaWorld or other aquariums without water leaking?

http://t.co/bUUXQhj Here is a example picture. How do they make it so the water does not leak out the sides? My guess is that they have a indent type thing in the cement and the pillars between the glass, and just slip the glass into the hole, and then add some of that water proof cocking stuff on the sides. Is that how they do it?