Tagging 'low point' on land below sea level?

I’ve had a look around and cant seem to find a way to tag a geographical low point on land that is below sea level. An example would be the Dead Sea or that place in Death Valley, i think. Are there any tags for this. Should I uses ‘ele=-20’ for example, and/or use a ‘natural=peak’ with it. (though it seems a bit odd to use that).

Any ideas? :slight_smile: