Lake volume is measured in acre feet of water. There is more water in Lake Cumberland than Kentucky Lake even though Kentucky Lake has more surface. Cumberland averages over 160 ft deep in the river channel at summer pool and even deeper sometimes. Kentucky Lake is long and broad but fairly shallow. Cumberland at its largest is about 63,000 acres surface area but most of that is over 100 ft deep so we are talking alot of water. I have fished both lakes and I can tell you even though Ky Lake Covers alot of surface it is fairly shallow compared to the lakes in Eastern Kentucky and Tennessee. Barkley is even shallower. Reelfoot lake looks big on the map but it only averages 3 ft deep so not alot of water (you hit a stump every 50 ft.). I grew up on Cumberland and when I went to Kentucky and Barkley for the first time I could not believe how shallow it was compared to Cumberland. To be in the middle of a bay and only be in 20 ft of water sometimes was hard to believe. It is nothing out of the ordinary to be a cast from shore and be in over 100 ft of water in Cumberland (even back in the creeks). Hope this helps.