Many governments have extensive websites (though keep in mind they won't always be in English). However, these websites can often be complicated or difficult to search.
One way to search government websites easily is to use the Google site: operator.
A search for information about the navy from the Australian government would look like this:
royal australian navy site:.gov.au
The first part is your keyword (royal australian navy). The second part tells Google to only return websites with the domain .gov.au, the domain used for Australian government websites. Make sure there is no space between site: and the domain.
See below for a list of other international government domains. Keep in mind the the US also uses .mil for armed forces sites.