The Siren Dress is based on deep sea ocean colors, mythological characters such as mermaids and sirens, as well as pinks based on corals. The bodice appears to be composed of scales. There are lines along the dress that glow in the dark, based on abyssal sea creatures. The apron is in a sea-shell shape and has the astronomical signs of Luna and Neptune embroidered on it (Luna stands for dreams, Neptune stands for water, both can symbolize delusion and deception). Alice's Omega necklace is tied around with seaweed.
The bow on the back of the dress is replaced by an angler fish, with spines fanning out and an angler fish's lure which also glows in the dark. Alice's hair also flows to the rhythm of water and her gothic boots are removed, rendering her barefoot. Her make-up has also changed and her lips are now the same pink as her dress.
Interestingly, the Siren Dress is coded to have underwater physics, allowing it to blend in with the aquatic setting of Chapter 2. However, this means that it appears to be underwater in any of the other areas as well; conversely, no other outfit displays underwater physics in the Deluded Depths.
Hollow Yves is again replaced, but to fit the underwater themes of the Deluded Depths, the human-like skull has been replaced with that of the skull of an Angler fish. The main difference, however, is the filament that sprouts from the top of the fished head normally is on the chin of the fish instead, and is extremely elongated to an abnormal size, making Alice look as if she has a tail. From this, we can tell that the dead Angler fish is in fact a female, as females are the ones that tend to have the filament and large teeth (however, only some of the fishes teeth are elongated). The bow is replaced with a large, thick "whisker" type abnormality that is present on either side of the fishes head.