Complex sentence: In 1963 the first branch, the Lighthouse Museum in the Rozewie Lighthouse was opened, in 1972 the Fishery Museum on Hel Peninsula, and the same year the Museum has been renamed to "Polish Maritime Museum" and was granted the status of a national institution.
Split into simpler sentences: In 1963 the first branch--the Lighthouse Museum in the Rozewie Lighthouse--was opened, followed by the Fishery Museum on Hel Peninsula in 1972. In 1972 the institution has been renamed "Polish Maritime Museum" and granted the status of a national institution.