After High Priestess attacks the submarine, Abdul will instruct everyone to flee to an adjacent room. You can choose to follow him, or decide to face her head-on, which will start a battle with you, Jotaro, Kakyoin, and Polnareff in the party. If you defeat her within 15 turns, you'll skip the scuba scene and you'll end up at the beach, where you find Midler without her teeth broken. You'll also get an FP bonus with the party members you fought her with. If you fail to finish her in 15 turns, the event will proceed as normal. If you picked the "Can't Swim" trait on the Charter Ship, there will be extra dialogue during the event.
During the scene where the group tries to pile compliments on Midler, your character will get extra lines when party members' FP is over 12 (10 for Abdul). If you're a male, you'll butt in with a witty remark, but if you're a female, you'll get jealous (female still makes a comment too, something along the lines of "even though I'm a girl... I still find you alluring").
When Jotaro is caught between High Priestess' teeth, you have a choice of trying to pull him out, which will cause events to proceed according to the original story, or you can try to smash the teeth. The latter will start a battle with you, Abdul, Kakyoin and Polnareff versus Teeth and Tongue, which will drop a Badge of Honor if you win. If your bad karma is 5 or over, you'll also get an option to run for it, which will increase your bad karma by 5 and decrease everyone's FP by 1 (-2 for Jotaro).