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.
A fern called the "deer fern" or "hard fern", Blechnum spicant, grows near Deildartunguhver. This fern grows nowhere else in Iceland.
- By comparison the combined flow of the 47 hot springs in Hot Springs, Arkansas is 35 liters/second and the water is 35 ° to 68 °. The Hay-Yo-Kay Hot Springs in Truth or Consequences, New Mexico has a flow of 99 liters/second. Lava Hot Springs in Idaho has a flow of 130 liters/second. Glenwood Springs in Colorado have a flow of 143 liters/second. The Dalhousie Springs complex in Australia had a peak total flow of more than 23,000 liters/second in 1915, giving the average spring in the complex an output of more than 325 liters/second. This has been reduced now to a peak total flow of 17,370 liters/second, so the average spring has a peak output of about 250 liters/second. However, there are many very-high-flow nonthermal springs; there are 33 recognized "magnitude one springs" (having a flow in excess of 2800 liters/second) in Florida alone. Silver Springs, Florida has a flow of more than 23000 liters/second.