Apex Lake is a location in Xenoblade Chronicles. It is located on the eighth floor of Frontier Village. A Nopon guide here provides transport from Frontier Village to the Eryth Sea, and thus all of Upper Bionis.
It is a round shining lake, with several grassy islands covered in flowers, with a fair number of Nopon NPCs on them, at least one of whom gives a quest. Berryjammy can be found here at night, and it is also the location of a Heart-to-Heart between Dunban and Melia - "True Natures".