Case in point, the “Horizontal Falls”. At low tide the water rushes through a channel in the rock, to seek an equal level, much like the Montgomery Reef thing. The zodiacs in these clips look like they’re just floating, but make no mistake, they were bouncing and sliding all over the place, and pretty much at full throttle forward, even though they look virtually stationary. Just a riot of currents and eddies and whirlpools, with just awesome power. (First pic is an internet shot, to give you a better overall idea of how it works)