Unless you suffer from riding in a small boat on a slightly rolling sea, no visit to Capri is complete without a boat trip around the island. A 2 1/4 hour circuit costs about 15e and if you want to enter the Blue Grotto its an additional 12e. There is a stop along the way where you transfer to a small row boat and duck under the low entrance to the grotto. Try to pick a sunny day as the brilliance of the blue is much more intense with bright sunlight. The reflected light in this semi sea cave is spectacular. When the seas are too rough small boating activities are cancelled.
The circular boat tour will ferry you up to and past all the main attractions including the Faraglioni, Green Grotto, Blue Grotto, the lighthouse, the Picola Marina. In between hundreds of hillside villas look out over the blue waters of the Bay of Naples. The cruise delivers scenic delights as well as informative narrative of the history and life of the island.
For the more adventurous, kayaks can be rented for 15e and hour. The Rough Guide suggests that a circular tour takes about 5 hours. Given the nature of wind and waves, that seems like an optimistic estimate.
Probably the most unpleasant locale on Capri is the Marina Grande. Its unavoidable unless you can afford to hire a helicopter to carry you back and forth. The marina is the main arrival and embarkation point between Naples and Sorrento as well as the start and ending point for most of the boat tours. Large ferries come and go during the day unloading hoards of day trippers who swarm mostly over the lower part of the island and Capri town. The cafes and restaurants that face the marina offer overpriced and tasteless snacks. By late afternoon or early evening the crowds leave making Capri a much more relaxing and enjoyable place. On can stroll the lanes of Capri town without bumping into groups of unruly sightseers.