The Blue Reef Aquarium sits on the cliff above Towan Beach and is the obvious wet-weather fallback. A walk-through ocean tunnel with sharks, rays, and a Cornish reef tank is the centrepiece; smaller tanks cover tropical species, seahorses, octopuses, and otters.
It is small but well done and easily fills an hour and a half with younger children. Tickets are cheaper if booked online. Combine with lunch in the town centre five minutes away.