National Geographic special

[DRE]

Jason,

a lot of wreck divers use what's called progressive penetration, where you go inside the wreck without the guideline (which some wreckers consider an entanglement hazard) but you try to memorize the area you're in as you go. This requires multiple dives to enhance familiarization. Needless to say, someone with proper cave- and guideline use training can go much farther much safer in a wreck, but then again that's part of the ongoing controversy between wreck and cave divers.
Personally I think going in any overhead environment without a continuous guideline is pure stupidity and is just asking for problems. A well ran guideline is the safest wreck diving tool ever...