Carson Beach, South Boston
How to get there: Take the Red Line to the JFK/UMass stop and then walk the 0.5 miles to the beach.
Carson Beach is connected to the L Street and M Street Beaches and together they form a large part of the waterfront in South Boston. This is the largest stretch of sand you’ll find in the city and it’s usually hopping on nice days. There’s even a renovated bathhouse with restrooms, changing rooms, and showers. Carson Beach also has limited free parking, but it can be tough to jockey for a spot.

Castle Island, South Boston
How to get there: Take the Red Line to Broadway and then take the #9 bus to E. Broadway at Farragut Road. Walk down Head Island Causeway to the beach.
Castle Island is most known for being the home of Fort Independence, but it also has a beach that faces the calm waters of Pleasure Bay. This makes it a terrific spot for swimming, and with summer treats like lobster rolls available at nearby Sullivan’s, it’s a great city beach destination. 

Constitution Beach, East Boston
How to get there: Take the Blue Line to Orient Heights and walk down Bennington Street to Trident Street.
Constitution Beach in East Boston is the spot to watch planes come and go from nearby Logan Airport. This sandy spot is a perfect place for families. It has a bathhouse, playground, picnic areas, and shade shelters. Grassy fields are great for a game of Frisbee, and there’s even a basketball court.

Front Beach, Rockport
How to get there: Take the Newburyport/Rockport Commuter Rail Line to the Rockport stop then walk the 0.5 miles to the beach.
Front Beach in Rockport is one of the few North Shore beaches accessible from the MBTA’s commuter rail. The sandy shore that awaits you won’t disappoint. The beach even has a swim platform about 30 feet out in the water. Front Beach is close to downtown Rockport, so it’s easy to stroll in for a bite to eat. The beach has public restrooms.

Spectacle Island isn't on T, but the ferry ride makes it a super fun summer destination! Photo by the author.

L Street and M Street Beaches, South Boston
How to get there: Take the Red Line to Broadway, then take the #9 bus to E. Broadway at L Street, and walk 0.5 miles down L Street to the beach.
Just a handful of years ago no one would have likely recommended spending the day at the L Street and M Street Beaches, but things have changed. This sandy spot is now nicknamed Southie Beach and draws crowds on hot, sunny days. There are public bathrooms and some free parking if you’d rather drive.

Revere Beach, Revere
How to get there: Take the Blue Line to Wonderland and then walk the 0.7 miles to the beach, or hop on the #411, #441 or #442 bus to North Shore Road at Oak Island Street.
Revere Beach was America’s first public beach and it still draws huge crowds during the summer. In addition to being a sandy spot just outside the city, the beach hosts many events during the year, like the Revere Beach Kite Festival and the National Sand Sculpting Festival. Amenities include a public bathhouse and plenty of nearby food vendors. There’s also some free parking near the beach.

Singing Beach, Manchester-By-The-Sea
How to get there: Take the Newburyport/Rockport Line from North Station to the Manchester stop. Walk the remaining 0.5 miles to the beach.
One of the area’s most famous stretches of sand, Singing Beach, has limited parking, so if you’re up for an adventure, try taking the commuter rail. There’s a $5 beach walk-on fee, so you might not save money, but you’ll likely avoid a parking headache. Amenities include a snack shack and a bathhouse with changing stalls and showers.

Spectacle Island, Boston Harbor Islands
How to get there: Take a Boston Harbor Cruises ferry from Long Wharf in Boston.
Okay, so Spectacle Island isn’t on the T, but you also don’t have to get in the car to get there. Take the ferry from Long Wharf in Boston and in 20 minutes you’ll be sticking your toes in the sand on Spectacle. The sandy beach has stunning views of the city skyline and the island boasts bathrooms, a food vendor, and nature programs.

Winthrop Beach, Winthrop
How to get there: Take the Blue Line to Orient Heights and then hop on a Paul Revere Bus to Winthrop Beach.
A lesser known cousin to nearby Revere Beach, Winthrop Beach is often populated more by locals than tourists. It’s a quieter spot to spend the day in the sand with great views. During low tide, walk out to the Five Sisters, wave breakers that protect the area from large swells. This hidden gem also has restrooms and some free parking.

Wollaston Beach, Quincy 
How to get there: Take the Red Line to North Quincy, then the #212 bus to Billings Road at Beach Street and then walk down to the beach.
Head to the South Shore to spend a day at Wollaston Beach in Quincy. This 2.5-mile stretch of sand has views of the Boston Harbor Islands and plenty to do other than just sitting under an umbrella all day. One end of the beach has a play area, lookout tower and picnic tables. The beach has restrooms, some free parking, and nearby options for food. 

Top image of Carson Beach courtesy of the Department of Conservation and Recreation.