The latest seed I played had a required item that lead to Mermaid Suit for progression on the D7 boss; however the D7 boss isn't reachable without Mermaid Suit since you can't surface in the room with the teleporter, and that is the only way to reach the D7 boss. The current logic doesn't have the Mermaid Suit requirement to reach the D7 boss, but it should be.
The latest seed I played had a required item that lead to Mermaid Suit for progression on the D7 boss; however the D7 boss isn't reachable without Mermaid Suit since you can't surface in the room with the teleporter, and that is the only way to reach the D7 boss. The current logic doesn't have the Mermaid Suit requirement to reach the D7 boss, but it should be.