Basket shows off a new ring of chests under the water on Iron Island, starts wiring up its item sorter, and finds the redstone leaks into the next chest at every curve.
Basket scraps the work done off camera, redesigns the top of Iron Island to be symmetrical, and starts a new set of paths that run right out under the ocean.
Basket fixes the item sorter again, adds more chests to the storage room, and starts dressing up the Iron Island iron golem farm with white glass and sea lanterns.
Basket studies a sorter that works, rebuilds the Iron Island item sorter around bone blocks, drains the old chests back through the system and lights the bedrock floor.
The water they have needed since the early episodes turns out to be right inside Drizzling Cove. Then a secret ladder shaft, a farm, and an island house full of silverfish.
Basket builds the fourth and last cell of the Iron Island mob farm out of prismarine, gets a top-up of blocks from johnfal_92, and wires a new collection point at the bottom.