Plot a quantity measured at several points on a map

Hi everyone,

I'd need to plot a quantity (sea bottom water temperature) measured at different points in the Laptev sea and east Siberian Arctic Sea.

I've never used Matlab to plot a map or quantities on a map. Here some questions:

1) where do I get a map of the focus area (and which format is needed)? I do not need an extremely high resolution

2) I know the locations where measurements have bene taken but I would like to have a map with color gradients for the quantity of interest, so to cover the entire region, and not just have a number of dots. Is the quantity automatically interpolated? According to which method?

3) I need to consider also other quantities measured at points. I was thinking of using kriging. Is there any up-to-dated kriging tool for Matlab (using Linux)? I've read about mGstat but I fear I might need Windows.

Thanks in advance for your reply and patience.

Cheers.