Ocean experts have long clashed over whether artifacts from the world’s most famous shipwreck should be retrieved for exhibits that could help people better understand the Titanic tragedy or whether they should be left untouched in the sea’s depths as a monument to the more than 1,500 people who lost their lives. James Cameron, known for his 1997 movie “Titanic,” sees himself as negotiating a middle path through this complicated and often emotional dispute.

Mr. Cameron dove 33 times to the shipwreck from 1995 through 2005, giving him a window on its condition and likely fate. His perspective is timely because the United States government recently sought to exert control over the wreck, raising questions about whether a company that has recovered more than 5,500 artifacts will be allowed to gather more.

Mr. Cameron’s views are also deeply personal. He often debated the retrievals with Paul-Henri Nargeolet, a French submariner who died in June while descending to the…