Somewhat Discouraging
Sorry Azoth.
First order of business, I'm going to assume you're ALL here, unless a player specifically tells me otherwise.
Anyway, calling up evokes no response. No windows are open from where you can see.
It's almost impossible to 'walk around' the building, as the Institute tower takes up most of the relatively small rock it's been built upon. Picture a crazy steampunk lighthouse out to sea. That's where you're at.
Looking around- no, no sea caves, again no room on the island. But that's weird. Just off the island about 30 yards or so, you see a tall metal rod tethered to a buoy (the rod is maybe twenty feet tall or so?). There's another one way out, about 100 yards it looks like.
Finally, despite your nice STR check, a 1 on a d6 would open most normal wooden doors. This door is far from normal. It's a giant metal sliding door- kind of like a barn door- with a big length of chain wrapped around the handle, complete with rusty old padlock.
You'd probably be rolling on the 'wizard lock' portion of the STR open doors chart, and I don't think a 15 has that option.