If you want an up-close look at a wolf eel or an octopus, check out this underwater sea-life display, housed inside and under a barge floating in the Inner Harbour. If you're at all claustrophobic, though, be warned: a dark staircase leads to a dark narrow tunnel 15 feet below water where you can see marine creatures darting about behind high windows. The more worthwhile experience is in the underwater theater where a 20-minute narrated dive show, run roughly every hour in summer (less frequently in winter), gives everyone a chance to view the more interesting of the 5,000 or so creatures in the tanks. The biggest room of all is the above-water gift shop. The site isn't wheelchair or stroller accessible, the windows are too high for small children (unless you pick them up), and the tunnel can get uncomfortably crowded. Tickets are good all day, though, so you can return later if need be.