With gas above $4 a gallon, summer is all about close-to-home vacations this year. An Andover native's new book about the Boston Harbor Islands can help you plan an enjoyable day trip.

Chris Klein, valedictorian of the Andover High School Class of 1990, researched the 34 islands for his just-released book, "Discovering the Boston Harbor Islands" ($17.95, Union Park Press). Now a travel and history writer, Klein combines those talents to help day-trippers learn about the historical military installations while enjoying what summer is all about — a relaxing day at a beach close to home.

"I think a lot of people are simply not aware that these islands are so close to Andover," said Klein, who grew up in western Andover and now lives in Waltham with his wife, Erin.

He said he enjoyed researching the history of the Boston Harbor Islands, as there is plenty to learn. For example, Fort Warren on Georges Island was home to Confederate prisoners during the Civil War, while Boston Light on Little Brewster is the nation's oldest lighthouse. Guided tours are available for this 76-spiral-step and two-ladder lighthouse and Klein said the city skyline view is terrific.

Getting to the islands is easy and inexpensive, said Klein. Ferry service runs from Long Wharf at Christopher Columbus Park in Boston and adult ferry tickets are $14 (visit www.bostonharborislands.org).

"It's just an easy-to-get-to destination that is an amazing resource. Bostonians have it right at their back door but just don't know it," said Klein, who spent more than a decade authoring business books and conducting market research for architecture, engineering and environmental consulting firms.

This reconnection to Boston's waterfront is partly a result of the city's massive Big Dig project and the cleaning of Boston Harbor and its islands. It's good news for Boston 'burbs like Andover, as residents can get a history lesson while enjoying the summer sun.

In addition to historical factoids about the islands, Klein's book sprinkles pages with portraits of people who have enjoyed the islands for years, like the keeper of Boston Light who was married there in 1994.

Klein felt it was important to combine today's generation of island voices with those of the past. As a result, the book does not feel like a history textbook; it's more like reading a story. Klein hopes it becomes a must-bring resource for day-trippers heading out to the Boston Harbor Islands this summer.