Charon

by Adalbert Zollern, Bella (Songshan) Guo, Brian Widerman, and RJ Antonello

Answer:
ESTATE SAILS

This meta uses the following answers:

PuzzleAnswer
AsphodelLET IT SNOW
Do You Like Wordle?GUTTURALS
Don't Know MuchTRAY CLOTH
GREEK COLUMNSAESTHETIC
IV GuysDRESSCOAT
Non-crosswordARTILLERY
Poetic JusticePLUTOCRAT
temporary nameRUSTY NAIL
The LaboratoryTELEGRAPH
Two Outs, Two Strikes, and...DISTICHAL
Why The Romans Never Invented Logic PuzzlesRELAXANTS

The answers are all 9 letters long. The flavortext refers to the Phlegethon, one of the rivers of the underworld. We can arrange our answers to form the other 4 rivers: the Lethe, the Cocytus, the Styx, and the Acheron. These rivers are connected end to end and flow from the top water icon to the bottom water icon. Looking at the left bank and reading down, we see the answer ESTATE SAILS.

TELEGRAPH
AESTHETIC
PLUTOCRAT
TRAYCLOTH
GUTTURALS
DRESSCOAT
RUSTYNAIL
RELAXANTS
DISTICHAL
ARTILLERY
LETITSNOW