Brian Savage and Colleen Ryan cruise to San Juan and the heart of Puerto Rico

Most yachtsmen cruising the Caribbean see the east sides of the Caribbean islands only once, as they arrive across the Atlantic. Thereafter, they hug the west sides, which are sheltered from the trade winds.

Puerto Rico is something of an exception, as its west side is exposed to northerly swells and has few comfortable anchorages. Instead, it is a Mecca for surfers.

In contrast the east coast, although exposed to the wind, has many small islands providing sheltered anchorages and offering protection against swell. Culebra is the easternmost island and from here a necklace of cays form a protective barrier to the north-east corner of Puerto Rico.

But be warned: though there are protected anchorages, the north-east, round Fajardo, is a busy tourist area with several large and expensive marinas. Snorkel boats, jetskis and other watersports boats invade the offshore islands of Palomino, Palominitos and Cayo Diablo every day. Puerto Ricans love their power boats.

The main yacht marina is Puerto Del Rey, where we were asked to part with a dollar per foot per day. Villa Marina, a couple of miles farther north, is cheaper, but visiting yachts are not so easily accommodated. The easiest option is to anchor behind one of the islands.

Most yachts favour Puerto Rico's sheltered south coast and so miss San Juan, halfway along the north coast. Yet it is a pity to miss this interesting city, with its mixture of old Spanish colonial architecture and modern high rise.

Puerto Rico has a rapidly growing economy and the new city of San Juan bustles with new buildings and smart cars and bristles with mobile telephones and excellent restaurants. The old town, still guarded by the fortress of El Morro, occupies Isla San Juan peninsula, stretching into the entrance to San Juan bay. There are two marinas right in the heart of the city on the border between the old and new towns. We stayed at Club Nautico.

If San Juan is your first port of arrival in Puerto Rico clear Customs and Immigration in the old town, near the cruise ship dock. Ask Club Nautico to telephone to register your arrival first.

Because there are no sheltered anchorages along the north coast we hired a car to visit the Arecibo Observatory and Caves at Camuy. Both are spectacular. Our first sight of the Arecibo radio telescope, the largest in the world, took our breath away. It is an enormous structure; set deep in the mountains and surrounded by forest.

A few miles from Arecibo, the River Camuy Cave Park is a 15km cave system carved from limestone by the persistent efforts of nature. The organised tours include a film and tram ride to the first cave. There is a massive 400ft sinkhole with an observation platform above and you wander through deep caverns propped by stalactites and stalagmites.

After an extended period of sailing the Caribbean, the bright lights of a boom city, coupled with Old World European charm was a welcome change of scene. A few quiet days in Culebra on the way back to the Virgin Islands provided a period of acclimatisation to prepare us again for island life.