So my mavic is at the bottom of a lake 20ft down. The gps gave me the dead spot and i have tryed scooping it out to no avail.

What i want to know is why! If the vps is supose to keep u 1-3m up with strong gps. Did i fly it steaight in...or... did i accidentally kill the power with the thumb sticks? And im guessing the sensors wont work over water.
Is there a way to find out from the flight data in the app? It shows me the movement on the map and spèed and altitudes but thats it.
Another fun part is the height is at -2m because it was closer to the water. Is there a setting that will prohibit you from going to negative height?

Might post your flight log and others can give you some answers.

Sorry to hear about your drone.

That's terrible

One thing you might have missed is that the VPS doesn't work right over water and, in fact, over any reflective surface... Simple put: it gets confused about the height. Most people say it's better to turn the VPS off when flying over water. It even gets confused when flying close over cars sometimes... If you're over such a surface you shouldn't pull down because it might go into forced landing.

It's best you upload your flight log so someone can tell you what really went wrong!
https://www.phantomhelp.com/logviewer/Upload/

I am very sorry for your loss. The height indicated depends on the height of your take off location which represents 0. If you fly lower than the take off location you will get a negative height indicated. As advised above I recommend sharing your flightrecord. People here might be able to tell you more about what has happened.

Sad to hear that. Another drone R.I.P.. But yeah as mentioned in the comments above VPS,water and reflective surfaces don't always get a long especially if flying over close to the surface.
Hope the experience doesn't put you off flying in the future though, we live and we learn.