We know a few things about Giant's Basin, and all of them are strange. It is a saltwater lake. Krytans fish in it. It is located directly north of Divinity Coast, Beetletun, and Lion's Arch.
It is also impossible for the above to be true. There is no single body of water that is directly north of all three locations. Conclusion: there are two bodies of water with the same name.
Why? And how do both of those large bodies end up being salt water anyway? Last I checked it is rare for a lake to be salty, and in most cases it is due to a lack of river outlet (eg Dead Sea). Now there is no visible outlet for these two lakes, and it is obvious by the proximity of the shiverpeaks to one and and th e northern mountain range to the other that the respective ranges are their sources (which is how lakes form on earth). Yet being farther north (which in Tyria seems to indicate higher elevation NB Ascalon being the "High Planes" settlement) and their proximity to mountain ranges indicates it is strange that they would not have large rivers flowing from them to the sea. There must be two(three) extremely large holes in the ground. Perhaps they really were created by giants, or glacier activity. But glaciers rarely leave such large area lakes.
Now there are some other odd things about the water table of kryta. Like the multitude of large rivers that can only be coming from a massive ground water supply, as they flow from no mountains or lakes. One of the rivers even flows into a basin, indicating that though it is much farther from the mountains than the basin, it is at a higher elevation. What is the source of this water? Simple precipitation? or a possible connection to the giant's basin(s)? There is also third similar body far to the west, north of the jungle, is it salty as well?
Here are the screenshots associated with my ramblings:
The Giant's Basin north of Divinity and Beetletun as named by the beetletun description
The Giant's Basin North of Lions Arch as named by a sign in DKNP
The unsourced rivers south of the East basin
the unsourced rivers south of west basin
And yes i suppose that people fish in them is not strange
edit: the screen shot required to prove the two bodies are separate would be too large, and its easy enough to see on the world map.