33 feet happens to be almost exactly 10 meters, so that's why the odd measurement. Vortex says a five minute limit. I don't recall any time limitation on the EOTech models that claimed they were submersible.

Battery life. I have an EOTech 552, which uses AA batteries. EOTech advises this for battery life:

Lithium: 1,000 continuous hours at nominal setting 12 at room temp.

AA alkaline: 600 continuous hours at nominal setting 12 at room temp.

There are 20 daylight steps (plus 10 more night vision steps) on the 552. So step 12 is just over halfway. I just checked my 552 and since there are 8 steps above the default power up step, it is starting at step 12.

So, I noticed when I was hunting over in the high desert at the peak of the day, I had to crank the power way up, at or near the max brightness. I'd get about a day of service from Duracell AA batteries, having to replace them shortly after using them sometime the next morning. In practical terms this was about 10 hours the first day plus maybe two or so hours the next morning, total around 12 hours. Note that my 552 has the F marking for enhanced electronics for longer battery life. The very early ones really ate up batteries.

AA cells are cheap, and I was loathe to go to a sight that used the more expensive 123 batteries. I hoped Eotech would come out with a AA optic like the 512 but with a 1 MOA dot only, and no 65 MOA ring. The only dot only model is the XPS2-1, which uses 123 batteries. These range from about a buck and a half for cheapies to five bucks apiece for high quality. I never bought cheapies because of worries of them leaking in a camera, but if they were removed from the EOTech after hunting, no worries.