calculate area of particular space in mesh plot

Hello All,

I am working a a bit of a creative problem and i am trying to calcualte the area of a certain part of my mesh plot. Essentially, in the mesh plotr there isna basin and then large ridges on each side of the low lying basin. I would like to try and calculate the the area of the low lying basin at the centre of the plot.

I was thinking if doing something like defining a boundary encompassing all z values of 0.001 or less?

If anyone has any ideas, functions, or code that they would think would work to do this I would greatly appreciate it.

Best,

Adam