If you are involved in an accident you'll be required to pay at least for the damage to the rented bike. Boats can be hired to cross the many rivers of Goa. This can be used for Arambol and places to the north. This ferry goes to Terekhol Fort, in the north of the state. The crossings are rather erratic and take between 30 and 45 minutes.
Buses wait on either side for the arrival of boats.
Ferries go every half hour to Divar Island from Old Goa.