Shouldn't the plural of meter be meters?
I just realized on my printed map, that there it's metres in both lenght and depht scale.
On further investigation it turned out that it is spelled like that throughout the programm...

We are UK based, so we use UK (or international) English, which use metre and metres. Although we don't have a US localised version of ReefMaster, we have tried to cater for our cousins across the pond by including feet and miles as measurement options!

Wow, I didn't know there was a spelling difference between UK and US for this word...
Sorry, my bad.

I'm from germany and fine with metric units ;)

There is all sorts of spelling differences between the US and UK.

Usually, they're close enough so native speakers can read it one way or the other.