Varna is home to the headquarters of the Bulgarian Navy and also the Naval Academy. It's no surprise then to find that the National Naval Museum is located here.
Unfortunately it was closed for renovation during my last visit (as is the website as I write this) and so I'm not sure about details of opening times and entry fees. The normal opening hours were 10-5 Tuesday to Sunday with an entrance fee of 4 Leva.
However even when it's shut there are several exhibits in the surrounding area of the Sea Gardens including the warship Druski. This boat's claim to fame is that it sunk the Turkish cruiser Hamidie during the 1912-13 Balkan Conflict.
If you're interested in boats, the Naval Museum is the place to visit. It houses a collection of various items connected to the history of Bulgaria's navy aswell as some boats which are displayed in the park outside the museum.
The museum is open from Monday to Friday from 10am to 6pm. Admission is 4BGN
It doesn’t need much presentation. If you are interested in naval things you have to see it. It collects the Bulgarian naval history.