The Mystic River may wind right around our city, but unless you own your own boat, it's difficult to make your way onto its waters. The nonprofit Boys & Girls Club of Middlesex County, however, offers a solution for aquaphiles. At their Blessing of the Bay Boathouse, all are welcome to rent canoes or paddle boats by the hour. As of this writing, the rates were a reasonable $10 per hour. But there's one catch. The boathouse is open only on weekdays. Sick day, anyone?