The Triple Helix drain kicks ass. Probably my favorite drain to date. There are three spiral staircases spread out throughout the drain. The first staircase is dry, the second is wet, and the third is dry and enormous. Biff and I just happened to stumble across this drain one day while doing recon. The one piece of advice i can offer is to bring your biff-boots.
Second Helix. Water cascades down this spiral staircase.