The National Parks Service is doing an Aquatic Intertidal bioblitz at the Boston Harbor Islands. Two Islands will be sampled, Lovell's Island and Thompson Island. This event is open to the public. Program fee is $7 and will cover ferry transportation.
Starts at 2pm and ends at 7pm with an option to stay longer for a cookout for an additional fee.
A bioblitz is a wildlife survey of all of the wildlife in a specific area where specimens of each species is taken, identified, and released. (although if you had a fishing license and wanted to keep some killis, it will probably be ok)
More information here: