To cite package ‘SOmap’ in publications use:

  Maschette, D., Sumner, M., Raymond, B. (2019). SOmap: Southern Ocean
  maps. Version 0.5.0
  https://github.com/AustralianAntarcticDivision/SOmap

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {SOmap: Southern Ocean maps},
    author = {Dale Maschette and Michael Sumner and Ben Raymond},
    year = {2019},
    url = {https://github.com/AustralianAntarcticDivision/SOmap},
    version = {R package version 0.6.2.9005},
  }