Regarding "safes" - if it's not UL- or ETL-rated, it's not a safe. Real safes are rated according to the number of minutes that they will withstand attack from a given set of tools in the hands of a trained safecracker.
From UL's site:
"Safes are rated for their resistance to attack against specific tools
for a set period of time. There are a dozen different ratings,
everything from ATM machines, to gun safes to bank vaults. For example, a
safe that bears a Class TRTL-15x6 rating, which might be found in a
jewelry store, should resist a hand tool and torch attack for a minimum
of 15 minutes. A TRTL-30x6-rated safe, which would protect important
documents or store money, should withstand an attack for 30 minutes. The
ultimate safe rating — a TXTL60 — should withstand an hour's worth of
attack that includes the use of 8 ounces of nitroglycerin."
Nearly 100% of "safes" that you will find in a big box store or online (even the imposing-looking gun safes) meet merely the minimum requirements for "residential security container" or RSC which is that they will withstand *5 minutes* of attack by common hand tools. They are not "safes" at all and give virtually no protection due to their thin steel and unsophisticated locking mechanisms. (Hint: if the description of the thing lauds what "gauge" the steel is, it's not a safe. Real safes start at 1/4" armor plate steel and go up from there.)
Here's a video showing that most "safes" are crap:
Therefore, with this in mind, if you buy a "safe" and not a real safe, it will only secure valuables against the dumbest criminals under time pressure, and if the burglar has any time at all to work on it with even the most rudimentary tools, it will be cracked.
Therefore, the only real use of a "safe" is to protect against fire and the subsequent dousing by the fire department - and again, if it doesn't bear a UL listing for fire protection, it's not a safe, it's just a heavy box. Again from UL's site:
"In addition to burglary protection ratings, UL also rates safes for
their fire resistance protection. Class 350 safes protect paper
documents, Class 150 safes protect magnetic tape and photographic film,
while Class 125 safes protect floppy disks. In addition to the Class
Rating, safes obtain an hourly rating for fire resistance — anywhere
from 30 minutes to four hours."
Waterproof safes are hard to make due to the fact that the door has to be sealed; therefore, for waterproofness, simply enclose your documents/valuables in plastic bags in a regular RSC as the more waterproof containers tend to be top-opening chests instead of front opening.
This should be enough of an education for you to pick your own safe.
AMSEC is a premier maker of safes and they start at $1000 and up. Sentry makes good fire RSCs and they start at $50 or so.