DMT, a psychedelic
tryptamine, similar in structure to the
neurotransmitter serotonin. The maximal effects last for a short period of time (5 - 30 minutes +), but it is considered to be the most powerful halucinogenic drug.
DMT experiences can include profound time-dilation, visual and audio hallucinations, and other experiences that, by most first hand accounts, defy verbal or visual description. Many accounts talk about perceiving other dimensions and traveling to the
end of the universe.