They do have a restriction on children under 5 and expectant mothers. This is for safety due to the motion on the boat. These boats tend to be rather open with people moving about a lot to see the whales or to deal with sea sickness. With a younger family, you might try going out on a sailboat tour. The seating around the cockpit is usually a bit more snug with less careening about.
You could take little ones but there is a lot of rocking and you would have to have hands on at all times
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