I am a summer person, I love warm weather, swimming and the beaches. This is a personal list of mine, not being from directly from Boston but an hour out I haven’t been to all the beaches nearby Boston but this is my list of the beaches I’ve been to and enjoyed the most around Boston.
To start off this list of my 4 favorite beaches near Boston I will start with, Constitution Beach, this is a nice beach in a suburb of Boston, Winthrop, right on the coast. This is one of my favorites near Boston because its about a 5 minute drive from Logan Airport and really close to downtown Boston. Also about the beach it has lots of seating space which isn’t always a luxury you have when so close to the city. But the beach also has plenty of free parking, restrooms, and you can watch planes fly right over you as you cool off in the frigid water of the northern atlantic ocean.
Next on this list is Savin Hill Beach, which is accessible off the red line on the T, the Boston public transportation. This beach is nice because its so close to the city which is really nice and it has the energy of the city. Again a lot of space to sit on the beach which is huge to me personally. This beach is cool though too because there’s a lot of cool places nearby to grab some food and also parks and baseball fields nearby for picnics and family fun. 
The next two are a little further out but still within an hours drive of the city. Plum Island one of my New England favorite beaches, located in Newburyport Ma. This beach is amazing, it is always fairly calm, there’s a lot of space on the beach and it’s a long beach as well. The only catch for this great sand filled beach is the parking can be tricky and fill quick but it is definitely worth it. The town of Newburyport is home to tons of great restaurants too so your always close to a great meal when here.
Lastly, my favorite of them all. Good Harbor beach, located in Gloucester Ma. This one is about an hours drive north of Boston, or an hour train ride from Boston. Gloucester is a unique town full of New England charm, there’s plenty of pubs and seafood nearby when at good harbor beach. This beach has surfing when there’s wind but its usually calm, the water is nice here and its a nice open beach though it does fill up with lots of people and get crowded. It is cool here when the tide goes out because you can walk out about 50 yards to Salt Island a tiny island with nothing on it right off the beach it is quite a sight! This beach has all the relaxation and beach needs with the New England charm as a cherry on top.