Deildartunguhver is a hotspring in Reykholtsdalur, Iceland. It is characterized by a very high flow rate for a hot spring (180 liters/second) and water emerges at 97 °C. It is the highest-flow hot spring in Europe.
Some of the water is used for heating, being piped 34 kilometers to Borgarnes and 64 kilometers to Akranes.
A fern called the "deer fern" or "hard fern", Blechnum spicant, grows near Deildartunguhver. This fern grows nowhere else in Iceland.