The gsw package is provided as a convenience for users
of the GO-BGC tutorial package.
Several gsw functions are called directly from the
tutorial package:
gsw_SA_from_SP
gsw_CT_from_t
gsw_pt0_from_t
gsw_rho
Only the code from the gsw package is included.
http://www.teos-10.org/ has the full code with
help pages etc. and instructions for installation
of the full package.