You cannot ride your bike on the Greenway itself, but rather ride alongside for half a mile on the dedicated bike lanes on the adjacent Surface Road.

BBC: In Boston, leaf peeping by bike

Visitors are required to wear a life jacket or wetsuit, you cannot feed the fish or submerge yourself beneath them, only three people (plus a guide) are allowed in the water at one time, and, no, you cannot catch a ride on their fin.

BBC: Swimming with whale sharks in Mexico

' He said 'Travis, let's go buy 10 Mercedes S-Classes, let's go hire 20 drivers, let's get parking garages and let's make it so us and a hundred friends could push a button and an S-Class would roll up, for only us, in the city of San Francisco, where you cannot get a ride.

WSJ: The Weekend Interview with Travis Kalanick: The Transportation Trustbuster