Most likely the name is metaphoric... as in, enter this area and wade into a sea of radiation.

Ok that works for me.

Perhaps like the Dune Sea in Star Wars.

Sanctuary Hills is actually located in https://www.google.co.uk/maps/place/394+Monument+St,+Concord,+MA+01742,+USA/@42.4718644,-71.3583774,2397m/data=http://forums.bethsoft.com/topic/1526246-the-glowing-sea/!3m1!1e3!4m7!1m4!3m3!1s0x89e39a25b5066e99:0x7b4c7a3fe91aad35!2s394+Monument+St,+Concord,+MA+01742,+USA!3b1!3m1!1s0x89e39a25b5066e99:0x7b4c7a3fe91aad35 area. The bridge next to the map marker is the one we see in the E3 footage that leads to the garage (the actual monument has been relocated and is now on the South side of the river next to the bridge). The exact location of Vault 111, taking map scaling into account, will be at the centre of the circular driveway Northwest of the marker, and the player's home will be slightly North of the marker.

EDIT: Newton is actual the area shown in the very last concept image where we can see all 3 nuclear detonations. Many people have assumed this image to be Sanctuary Hills, but the layout is completely different.

This has never been confirmed as being the Glowing Sea, it has been assumed due to the way the footage was presented at the time. All Todd says is that the Glowing Sea is located "where the bomb fell". This could refer to any of the nuclear detonations in the area, including the one that hit the harbor.

When I mentioned the possible expansion of Project Purity, I was talking about the tech being replicated and then rebuilt in the area of the Commonwealth. The presence of a perpetual source of radiation in Boston Harbor would be more than enough reason for Madison Li to want this tech to be tested out in the Capital Wasteland so that she can bring it back with her when she returns to the Commonwealth after the events of Fallout 3.

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But the starting area is spitting distance from concord, I mean I know the game has to be scaled down but its not that scaled down. How is it even possible that sanctuary hills is that far south?

I completely agree. The map marker I have just posted is in the Minute Man National Historical Park, which is slightly Northwest of Concord, not South of it. The location I have shown matches perfectly with the E3 footage when we call the vertibird. Concord can clearly be seen in the background as the vertibird takes off.

Wait a sec there are two concords my bad.

EDIT which is really weird i might add.

Something else very significant about this particular location can be seen if we zoom out slightly on the https://www.google.co.uk/maps/place/394+Monument+St,+Concord,+MA+01742,+USA/@42.4718644,-71.3583774,2397m/data=http://forums.bethsoft.com/topic/1526246-the-glowing-sea/!3m1!1e3!4m7!1m4!3m3!1s0x89e39a25b5066e99:0x7b4c7a3fe91aad35!2s394+Monument+St,+Concord,+MA+01742,+USA!3b1!3m1!1s0x89e39a25b5066e99:0x7b4c7a3fe91aad35. Leading directly into the route taken by the protagonist during gameplay, we can see Highway 111 coming in from the West as it crosses Highway 495 (which is a Blue Star memorial Highway, as in the Blue Star reference on the refrigerator in the player home). Also, where Highway 111 meets up with Highway 2 (which relates to our 2 possible protagonists), there are 2 more roads, one running North and the other South. The North road is called Taylor Road, as in Courtenay Taylor, and the South road is actually called Piper road, which matches the name of one of the 4 known companions.

Basically if its inland there are a couple of things it could be,

If they used a penitraror type warhead in the low megaton range it may be a crater and lake similar to this...

http://www.amusingplanet.com/2014/03/lake-chagan-atomic-lake-filled-with.html

Given the location of several real world military bases associated with either a real world power plant or a reasonable expectation of having a nuclear stockpile on base, that is located where you can get a reasonable blast crator to basically creat a nuclear lake due to terrain....

Well let's just say it's not impossible to create a super radioactive lake that makes Lake Karachay look like a Lake that even Greenpeace would swim in.

As for how it would work....basically if the crator is more ur less filled with a combination of broken nukes, spent reactor fuel and one or or more industrial ore utility scale reactors is dumped into said crator, water may be what triggers nuclear reactions, said reactor would heat up when the weight of the water over the pile pushes water into the pile until the water goes critical, heat transfers to the the water until it starts To circulate, the hot water on the surface starts to expand until the reactor is running hot enough that you start to see what looks like boiling water (at this point it's actually a mix of boiling water and thanks to the extreme heat at the pile dissacoceated hydrogen and oxygen )

Now for the bad news.

If water for some reason is not replaced as fast as it boils off, the water level will drop.....

Why is this a bad thing?

https://en.m.wikipedia.org/wiki/Limnic_eruption

Replace magma with runaway nuclear reactor, and co2 with boiling water, steam, superheated hydrogen gas and oxygen gas. Literally an instant thunderstorm. Worst case it's literaly Old faithful scaled up to a kl across, and with a radioactive dust kicker. Best case it's a lake that periodically boils over as it dumps heat, creating a basin of dead soil as normal temperature life is literaly boiled boils death every few days then retreats as rhe water boils off, incidentally killing any life that can survive in super hot water as it dries on the cooling soil or water.

Now realize that's not the end of the problem. The steam explosion dumps a lot of heat out of the system. If there was a twin lake setting similar to the above nuclear crator lake, you will then have an inflow of cooler water into the crator, and the core will also be outgasing steam, basically cooling down the pile as the reaction temporarily slows down, once the lake fills sufficiently to push water back into the reactor things start over again....

Basically for this to work you need an enclosed basin, and a way to refill the basin fairly quickly. An open basin like Boston harbor would flush out the heat far too quickly for there to be mutch of a hot water buildup, but a semi enclosed space Inland probably would, preferably land that was predisposed already by its drainage basin to form a crater and lake formation, or some of the converted costal swamplands

Essentualy the original swamp next to the crator would become a dead zone as super hot water expands out of the crator, cools then flows back into the crater. Basically any of the old seaplane basses might do as long as the drainage to the ocean was sufficiently restricted .

That was a pretty dang good post Drakenred.

(I am still a tad more inclined to Gk's vision but thats a grand idea as well)

I just have a problem with a port town calling something a sea if there is not water in it all the time, It could happen humans are strange but 2-caps just would not take it well.

"Nope pointing at the water that there's not the glowing Sea, Thats the Salt desert. You need to head back -that-a- way for bout 35 miles to the dust bowl looking place. Heh he, look at your face you musta had a hellva time getting here, You sure ain't the first to see the ole lighthouse, and the shipwrecks from afar, and make the mistake. I can tell your no townie cause of that blue suit." Stated the fisherman mockingly.

2-caps hand slowing inches towards his hip holster.

I have to agree with 2-Caps here. With Boston being a major port location, it would be hard to believe that the locals would call an entire area a 'Sea' if it didn't actually include a large body of water. Also, the formation of thunderstorms requires huge amounts of moisture that would not be found inland, especially due to the dry, arid nature of the Commonwealth Wastelands. Because the storms from the Glowing Sea are also highly radioactive, any radiation would need to be in the same place as the water source that the storm is created from. It has to be at the point of origin for the whole idea of irradiated lightning to make any sense.

Actually no bombs hit Boston; all of the damage was caused during particularly rowdy St. Patrick's day celebrations in 2077