THEME:   SUB is needed to make sense of 9 (nine!)  maritime clues   
GOOD ONES:     Answers to starred clues {& theme}   SUB   
Lab growth below sea level?   (SUB) CULTURE [not sure subculture is used by any but the troglodytic lest it offend those so grouped --- I still use it]   
Underwater speaker?   (SUB) WOOFER   
Scenery for "Operation Petticoat"?   (SUB) SET      
BTW:   Starting lineups   A-TEAM [only if you're lucky --- needs "at times" given all the injuries]      
Copycats   APES [I get it, but I'm tired of this combo.  Here we have an opportunity for a biological reference, which are too rare in Xwords]         
RATING:    
 
  
 
Three grins = Loved it; Two grins = Enjoyed it; One grin = A bit bland for my taste; One teardrop = Not much fun