Sneaker waves are in this black sand beach in Reynisfjara

WARNING: REYNISFJARA BEACH HAS CLAIMED THE LIVES OF VISITORS. HERE IS HOW TO STAY SAFE
Sneaker waves make Reynisfjara beach one of the most dangerous destinations in Iceland. However, with the proper precautions, you can avoid yourself or your loved ones, adding to the number of lives lost there. The South Coast of Iceland lies along the open sea of the North-Atlantic ocean that brings powerful waves up to the coast. The tallest waves measured there (and anywhere on the planet) rise to 40 m (120 ft), similar to a 10-story building.
Sneaker waves (also known as sleeper, king, or rouge waves) are huge coastal waves that can suddenly appear in a train of smaller waves. The sneaker waves are much larger than those in between and reach way further. The time between the giant waves can vary, sometimes, one comes right after the other, or there can be up to tens of smaller waves in between. The waves can rise very fast just before hitting the shore. This happens because the ocean floor deepens rapidly away from the coast. In addition, the ocean currents are very powerful and add to the danger.
Other dangers in Reynisfjara are from rockfall and rockslides. The cliffs above the Eastern part of the Reynisfjara beach are steep and unstable, so rockfall is common. When an ocean wave grabs you, you are knocked off your feet and it is very tough to stand up and find balance again. One of the reasons for that is that the wave creates a suction that drags you out and washes the sand and gravel from under your feet. Once you are in the water, the currents will pull you away from the coast and nothing can be done to save you. The water is also freezing and you suffer from hypothermia within just a few minutes.