mesoscaphe
/ˈmɛsə(ʊ)skeɪf/(also mesoscaph) Now historical
noun
A submersible vessel designed for exploration of the sea at moderate depths.
Origin
1950s; earliest use found in The Britannica Book of the Year. From French mésoscaphe from méso- + -scaphe (in bathyscaphe: see bathyscaph(e).