Flooded Theta Passage

It's the Theta Passage, but with the main plane in the middle all full of the sea. All that remains is the four corner bits, and only a narrow passage connecting them.
-README- Flooded Theta Passage It's the Theta Passage, but with the main plane in the middle all full of the sea. All that remains is the four corner bits, and only a narrow passage connecting them. Will you brave the trecherous pass to attack