Linden Viewers - not recommended
The latest viewers by Linden Lab have removed the -loginuri and -loginpage options, so it has become very difficult to use them with OpenSim grids such as Ocean Grid. It is still possible to use them but you need to alter XML configuration files instead. Linden Lab provide some rather complicated instructions to do this.
Previous viewer code, including Viewers 1.x, 2.x and 3.x, were compatible with grids based on the OpenSim server code. These basic viewers used the switches -loginuri and -loginpage. If you know how to do this already and are using an old viewer, you can use these details:
-loginuri http://oceangrid.net:8002/ (insecure port, not recommended)
Since using a Linden Viewer to connect with OpenSim requires some technical fiddling and doesn't allow easy switching between grids (or forces you to use an old viewer), it is now so complicated that we recommend that you no longer use the standard Linden Viewer to connect to OpenSim grids like Ocean Grid.