1805 Description of Durham's Lake
At the bottom is a basin of excellent water, which measured twenty feet to the place where it came into contact with the rock, terminating the cave as far as it has been or can be yet explored.
Beyond the meeting or the rock and water there is a conduit running farther into the earth, than could be measured with a long pole; and is, undoubtedly continued, through it may ramify into many subordinate channels, before it advances to the beds of the river and creek.
The many springs on the verges, the proportional rising and falling of the waters in the river and creek, demonstrate the connection and prove the surface of the one to get on a level with the other. When there is a high fresh in the river, the lower chamber is nearly filled.
Durham's Lake Today
Today Durham Cave's "lake" is often dry in the main part of the cave, however the sump basin always has water in it.