The Rv13 under the Horgefjord between Stavanger and Tau is the longest and deepest undersea road tunnel in the world: 14.5 kilometres long and up to 292 metres below sea level.

The Ryfylke tunnel is the main part of Ryfast, which opened in 2019 and replaced the Lauvik to Tau ferry. The crossing was among the busiest in the country, and the queues at Lauvik were a fixed part of everyday life across Ryfylke.

The tunnel has two bores, one for each direction. Shortly after opening it drew criticism over tolls and a few tunnel fires that closed the link for hours, which has made the status especially important for commuters between Tau and Stavanger.