From Portsmouth if you travel north you can get to the end of the island and see some of the offshore islands and also Guadeloupe on a clear day.
When you ask a guide to quote you the price for a trip on the Indian River, be sure to clarify the following:
The currency (the currency in Dominica is the East Caribbean Dollar), when we were quoted a price the guide said 20 dollars. We made the mistake of "assuming" he meant 20 East Caribbean Dollars and not American Dollars, that was a big mistake.
When I asked the guide about this mistake, he told me that he had said USDollars, I am sure he had not. The point is make sure...