I grew up with this knife in our home and was told it was a souvenir my Dad brought home.  He was a veteran of the U.S.Navy in the Pacific Theater during WWII.  Unfortunately the knife was stored away & one of the things we didn’t remember to discuss when Dad finally began to talk about his war experiences just a very few years before this death in 2022 just shy of his 96th birthday.  My research indicates this knife is a Navy diving knife. I’ve found many different versions of diving knives, but none exactly like this one.  I understand markings were forbidden by the U.S.Navy, and this one has none.  The handle appears to be wood, the sheath appears to be brass & is very heavy.  It’s priceless to us, so we don’t care about the value, but would like to have its country of origin and possible dates identified. Any help will be greatly appreciated.

While I don't know anything about your particular knife, I own several US Navy versions of it. They all have maker markings on them. Whoever told you about markings being taboo, that is not true.

I don't believe this is a US WW2 diving knife.  Several different companies made them, and some are marked and some are not.  The WW2 ones were made to a specification, and were still made to that specification in the post-war period into this century.  Two possibilities, it's pre-WW2 or it's foreign made (maybe British, possible Japanese).