Pipeline is not a beach. It is a wave, and it breaks a short paddle off the sand at ʻEhukai Beach Park, on a shelf of lava reef that sits close enough to the surface that surfers talk about it in terms of how many feet of water are over it rather than how many fathoms. That geometry is the whole story. Swell arriving from the North Pacific runs into shallow rock and throws forward all at once, producing a barrel wide enough to stand in and a lip that lands with the weight of a wall falling over.
It is the most closely watched wave in surfing and, by common agreement among the people who ride it, the most dangerous. The danger is not drowning in open water. It is the reef: the wave holds you down, and the bottom you are held against is sharp, shallow and unforgiving. Surfers who have made careers here still describe it as a place that gives no second chances.
There are really three waves at this spot. First Reef is the famous one, breaking close in on ordinary big days. Second Reef breaks further out and starts to work when the swell gets large enough that First Reef cannot hold it. Backdoor is the right-hander that peels the opposite way off the same peak, and on the right swell direction the two run away from each other from a single takeoff.
For a visitor, Pipeline is a spectator attraction and should be treated as one. In winter this is the best free grandstand in surfing: you stand on the sand at ʻEhukai, forty or fifty metres from the takeoff, and watch professionals do something genuinely difficult at close range. In December the coast's biggest professional event has historically been held here, and the crowd is a North Shore institution in its own right.
In summer the whole thing vanishes. The swell shuts off, the reef sits under flat water, and people snorkel over it. It is the same rock.