I have written previously about Gordon Douglas (Nov 7 2014, Apr 4 2016, May 11 2019), a protean director who worked his way up from short films to well-crafted B genre films; Westerns, science fiction, melodramas, etc. He also has shown skill directing low-level actors -- as in Mara Maru -- on their way up (Ruth Roman) and on their way down (Errol Flynn). Mara Maru (the name of a ship) has a story (by N. Richard Nash and Philip Yordan) that is derivative of a number of other Warner Brothers films, particularly John Huston's The Maltese Falcon (1941) and Michael Curtiz's The Breaking Point (1950), about a search for a missing treasure. Errol Flynn, whose dissipated appearance works well for his exhausted character, and Ruth Roman, the ambiguous femme fatale, sail with villain Raymond Burr in the Philippines, looking for lost diamonds. It's a rather rousing film, the diamonds being found at the bottom of the ocean in a typhoon, turning out to be on a cross missing from a cathedral.
The dark and beautiful black-and-white cinematography is by Robert Burks, who had done Strangers on a Train for Hitchcock the previous year and would go to do Rear Window (1954) and Vertigo (1958). The intense score, with its hornpipes and other nautical motifs, is by the prolific Max Steiner.