Admission is free, parking is tough. There are no lots immediately adjacent to the aquarium, but meter parking one street over. It took us quite a long time to find a spot as the area is popular with tourists. It’s not an all day aquarium. The first time we went, the kids were 5 and 7. It took about an hour to get through that day, mostly because my daughter was interested in the touch tank upstairs. Today I only brought my 6 year old son (no interest in the touch tank ah all) and it only took about 20 minutes to do the whole aquarium. Parking is $1/hour on the meters. They have had harbor seals in the past, unfortunately the two they had passed away recently. It does sound like they will reopen the seal exhibit soon.
This would be great to combine with the cape cod children’s museum (previously blogged) in Mashpee to make a day out of driving to the Cape!