dcw-gmt : The Digital Chart of the World for GMT 5 or later ( https://www.soest.hawaii.edu/wessel/dcw/ )
gshhg-gmt : A Global Self-consistent, Hierarchical, High-resolution Geography Database ( https://www.soest.hawaii.edu/pwessel/gshhg/ )
gsw-c : TEOS-10 GSW Oceanographic Toolbox in C ( https://github.com/TEOS-10/GSW-C )
Add an ebuild in portage :
The ebuild is now in the portage tree.
You can also use layman : emerge layman then layman -a gsview-overlay
For Paludis use this rsync : rsync://gentoo.zugaina.org/gsview-overlay-portage
If you have a problem : ycarus(-at-)zugaina.org