MD
This is NOT personal experience, just some research I did on my own. Goodenough springs exits from the bottom of Lake Amistad. Supposedly it is a somewhat extensive cave system and there is *supposed* to be a permanent guideline installed once you get inside. The information I have seen came out of several books and I would have to refer back to them for specific info. If I can find the info again I will be glad to share it with you as well as the specific book it came out of.
My recollection is as follows.
The spring entrance is at the bottom of lake amistad. Vis in the lake is usually less than 20' due to algae bloom, etc. Supposedly there is a somewhat dense covering of hydrilla on the bottom as well. Amistad is in a state park and the parks and wildlife or some other agency supposedly has a bouy in the middle of the lake. This bouy is said to be anchored at or near the mouth of the spring. I have been told that this spring is an EXTREMELY high flow for the first 30 yds or so, then it opens up into a larger room where the flow is reduced considerably. The depth of the opening is supposed to be around 130' so the flow and depth factor make this an extremely advanced and challenging dive. I only personally know one other cave diver, and I am not sure either of us has the experience to do this particular dive, tho the idea has intrigued me ever since I heard about it.
I will try to find some more specific informatio that I had collected on this for you, and if you get the idea to put together a trip there, I might be interested in going.
Dive often, but dive safe.
John