Just walk down 10 min to the fort and the old garden. FREE.
you do not need to book with the cruise, just walk down the pier for 10 min and you will get to Murphys... $29.99 1 lb lobster meal, worth it!
This one is a must see. Go there once is all you need though. DO NOT GET NEAR THE WET BLACK ROCKS; DO NOT RUN in the area. I witnessed an older gentlemen fractured his ribs and head because he fell on the rocks (I found out later on)
home port, board the ship orderly.