Based on Null's translation, it's also windless, so it's very much like the calm belt.
http://groups.msn.com/OnePieceMangav-3/chapter376.msnw?action=ShowPhoto&PhotoID=7611
On the other hand, in this scene:
http://groups.msn.com/onepiecemangav-2/416mq.msnw?action=ShowPhoto&PhotoID=8456
you can clearly see waves, which are not present in the calm belt. Perhaps it means that though the sea is windless it's not currentless, or perhaps it's more evidence for the theory that the waterfall at Eneas Lobby is creating a current through the calm-belt-like sea for ships to travel on.
This line in the raw goes like: そして扉の向こうには”偉大なる航路”をはさむ「カームベルト」のような大型の海王類の巣が広がって普通の船じゃ入り込めねぇ
It doesn't say anything about being windless. It only says it's the home to the large Sea Kings like the ones found in the Calm Belts.