There are several different synonyms for the term "submarine diver". One of the most common is "deep-sea diver", which refers to a diver who specializes in exploring the depths of the ocean. Another popular synonym is "underwater explorer", which can refer to anyone who dives beneath the surface of the water to explore or perform research. "Seafarer" is another term that can be used to describe someone who works underwater, while "aquanaut" specifically refers to a diver who uses special equipment to conduct experiments and research below the surface. Other potential synonyms for "submarine diver" can include "oceanographer", "marine biologist", "shipwreck diver", and more.