frozen? yes
sucessfully ? if by that you mean will it freeze solid? yes

edible once defrosted, matter of opinion.
I wasn't a fan of the consistency once thawed, come mid winter that may change.

cut into 1"x1" chunks, get as much seed out as you can, put in freezer safe container, freeze.

Yes. I do cantaloupe and watermelon all the time. My method is to cut into 1" or so chunks, place on cookie sheet lined with Saran Wrap and freeze. After frozen spray the chunks with water and back into freezer to freeze again. Then vac seal in bags. The trick is to only partially thaw before eating.

jt

Or you could freeze watermelon puree to make watermelon lemonaid when lemons are in season in the winter.

The watermelon will not stay solid once its frozen and thawed. Freezing will break down the cells and it will get mushy. Cantaloupe is a bit more dense, and can hold up better to a freeze/thaw

I don't think thawed watermelon is any good (I agree with ksrogers that it gets mushy) but I love it as quick watermelon sorbet. I freeze it in 1-2 inch chunks (seedless or with seeds picked out) and pack the frozen chunks in ziploc or vacuum bags. I blitz the chunks in a food processor with a little lemon juice and maybe a little sugar, depending on how ripe the melon is, and serve it right away. It tastes intensely watermelon-y and is fantastic after the season's over. The ziplocs will last just a month or two, but vacuum bags will keep it fresh well into the winter.

We also use the watermelon chunks to make frozen watermelon margaritas. Add tequila and lime juice and a little water if needed to get a drinkable consistency. Because it's more liquid, a blender will work fine--you don't need a food processor.

I freeze in chunks because I'm usually too busy to do otherwise at the time. When I defrost, then I puree, pour the puree into popsickle and/or push-up molds and freeze. You can also slip this puree into Jell-o instead of some of the liquid.

i put a whole watermellon in my freezer for 24 hrs, cut it open and was still in solid form and was very cold and sweet. Apparently the thick rind saved it from turning to mush

I can tell you I did the same thing. I put the whole watermelon to freeze and i forgot about it for three days (it was on my extra freezer) i took it out and only allowed for the outer layer to defrost I then began to cut the outer layer out and cut it in slices it wasn't easy but really worth it, you want to eat it while still in its frozen state other wise it does turn mushy. it was really good i was surprised of the results.