For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:Subsurface-Divelog/openSUSE_Tumbleweed/home:Subsurface-Divelog.repo
zypper refresh
zypper install subsurface
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:Subsurface-Divelog/15.6/home:Subsurface-Divelog.repo
zypper refresh
zypper install subsurface
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:Subsurface-Divelog/15.5/home:Subsurface-Divelog.repo
zypper refresh
zypper install subsurface
For 15.4 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:Subsurface-Divelog/15.4/home:Subsurface-Divelog.repo
zypper refresh
zypper install subsurface