Silt-out

A sudden loss of visibility when fine sediment is stirred into the water, turning a dive into zero-visibility conditions in seconds.

A silt-out is the sudden, near-total loss of visibility that happens when fine sediment on the bottom or on ledges is stirred into the water column. One careless fin stroke over a muddy lake bed, a wreck's silty corridor, or a cave floor can drop visibility from 10 m to zero in seconds, and fine silt can hang suspended for hours.

In open water a silt-out is disorienting; in an overhead environment it is life-threatening, which is why cave and wreck training is built around preventing it: precise trim, frog kicks and modified flutter kicks that direct thrust up and back, staying well off the bottom, and always running a continuous guideline to the exit so the team can follow it out by touch if the water goes black.

If you are silted out, stop, stabilize your buoyancy, and make contact with your buddy and the line rather than swimming blind. Recreational divers meet mild versions on muck dives and training platforms; treating every silty site with cave-style propulsion discipline keeps the viz, and the photos, intact for the whole group. Your first stirred-up training platform is the cheapest version of this lesson you will ever get.