The tunnel flooded on 16 August 2003 after the automatic pumping system failed to sufficiently drain the natural reservoir for water. This caused the pumps to malfunction and it took a week to drain the tunnel for of water and allow it to open. This was the first time such an event occurred in a subsea tunnel in Norway. A 12-tonne concrete section fell down 28 December 2003, causing the tunnel to close for a week. The tunnel was closed again on 16 January 2004 after geological surveys found a section of unstable rock. Further surveys revealed that the geological evaluations during construction had overestimated the quality of the rock and hence not implemented sufficient countermeasures. As a temporary measure a tentative ferry service was established from February. The issues cost NOK 35 million to resolve, and the tunnel could re-open on 2 April.