Had a wee father son day out here with the laddie. It was a good day, and the Sea Centre kept him amused for a good wee while. Enjoy the wee quiz they gave us, made learning fun, and was a good way to get my son reading the information points rather than just looking at the marine life on display. We went up to the viewpoint on level 4, and this is accessible as are all floors by lift. The viewpoint would be breathtaking on a beautiful day. Unfortunately, there was a lot of overcast when we were there. Cafe also has nice views, but the menu, although relatively cheap, is limited food wise. Does, however, have the benefit of Costa in it, so coffee was good.
All in all, good wee day out admission is expensive in my opinion at £40 for 1 adult 1 kid but nicely laid out and gift shop isn't expensive.