Tornado spouts formed out of sea water and about 500ft tall were seen on the English Channel on Monday.
Experts say tornadoes and waterspouts are not too uncommon
Dover coastguard crews saw three spouts moving across the water at about 25mph, about eight miles offshore.
A spokesman said the rarely-seen weather phenomenon is caused by convection currents which pull water towards the sky in a circular motion.
Meteorologists said waterspouts are more usually seen in late summer or autumn, when cold air hits warm water.
Crews were alerted by ships in the Channel and were able to see the spouts from their base at Dover, the spokesman said.
He said: "The cloud forms circles at the top and the spout then spirals all the way down to the sea."
He added that the waterspouts were moving along at about 20 knots, or about 25mph, "skipping along on top of the water".
The coastguard explained that the waterspouts move at the same speed as the clouds.
He said the waterspouts were not dangerous to larger vessels and would have had a width of about one metre.