Popham is pretty nice. I used to camp there in mid may before the summer when it was not as crowded and surf with the seals.
. That part of maine is not near major population areas anyway. I think probably Acadia can get more crowded in the summer.
The first time I ever heard Alex Jones was when I was camped there on the beach listening to short wave radio in 2004. That campground may be gone but hermit island is a good place to camp nearby.
If you walk up to fort baldwin nearby, you can get a good view of the coast from the hill and it is a very short walk
http://www.mainetrailfinder.com/trails/trail/popham-beach-state-parkThis is what the fort looks like, I wouldn't be surprised if it was haunted:
https://andrikyrychok.wordpress.com/2009/04/19/fort-baldwin-a-piece-of-maines-military-history/
view of the coast from the fort

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Another spot is Reid State park on the coast. It's not far away from popham but there is an inlet so you have to drive way around
https://www.google.com/maps/uv?hl=en&pb=!1s0x4cad9e69b715e175:0xefd5ae2e9c36dce8!2m19!2m2!1i80!2i80!3m1!2i20!16m13!1b1!2m2!1m1!1e1!2m2!1m1!1e3!2m2!1m1!1e5!2m2!1m1!1e4!3m1!7e115!4shttp://www.stateparks.com/reid_state_park_in_maine.html!5sreid+state+park+-+Google+Search&imagekey=!1e1!2shttp://www.naturallyamazing.com/americasparks/3047.jpg&sa=X&ved=0ahUKEwjfnveGvqLTAhVj54MKHQ7pDTcQoioIfzAKhttp://www.mainetrailfinder.com/trails/trail/reid-state-park=====
There is probably a high speed ferry that runs to Yarmouth Nova Scotia out of bar harbor Maine, I used to take that and then drive a few hours up to Port Joli and that area which can have great surfing during atlantic hurricane season but that part of Nova Scotia is super nice
http://www.ferries.ca/early-booking-bonus-on-the-cat/?gclid=Cj0KEQjww7zHBRCToPSj_c_WjZIBEiQAj8il5IP2i8d4sX-UrnIWtapjTg0OUh0_X4dpbLYHwtOPp3MaAoQU8P8HAQ=====
The biggest beach resort area is old orchard beach which has rides, nigh clubs, live music ..
Other decent beaches are York beach, Ogunquit, and Kennebunk. The traffic and crowds can be a little lighter at Wells beach .. but on a hot day most of the beaches are jammed. The beaches are mostly south of Portland. Except for a few beaches like popham, most of mid coast Maine is rocky.
Besides LL Bean, Kittery trading post in Kittery is a mega outdoor store. There is a giant Cabbelas in Sacrborough right off the highway. Those places have large selections of guns, used guns, Archery, Hunting, camping, outdoor gear etc .. I recommend the Thai Restaurant across the parking lot from Cabbelas.
Sebaggo Lake is known for landlocked salmon ..
Baxter State park has mount Katadin, a major peak. Camping at Abol Bridge is a good spot on the river. People raft the Penobscott west branch there which has huge rapids as does the kennebeck gorge - another popular rafting river.
The drive up to Jackman Maine through Salon and the forks on 201 is pretty wild and scenic also and has some historic landmarks due to military expeditions into Canada in colonial times via the river etc. My camp is just south of that area ..
Pennobscot Bay is a large bay with many islands and seems popular with sea kayaking as people kayak between the islands or perhaps camp on them ..
There are some small amish communities in Maine. I think one is in Unity. There is a small shaker villiage near Lewiston