The line is 27.9-kilometre (17.3 mi) long, and is currently owned and operated by the BLS AG railway company.

The two lakes are linked by a 5.5 km (3.4 mi) stretch of the Aare through Interlaken, but the river is not navigable, dropping some 6 metres (19.7 ft) and passing over several weirs.

[1] In 1872, the first part of the Bödeli Railway was built, from Därligen, on Lake Thun, to what is now Interlaken West station.

[1] Bönigen remained the eastern terminus of the line until 1969, when passenger service was cut back to Interlaken Ost station.

[3] With the 2020 timetable change, BLS dropped service at the three intermediate stations between Spiez and Interlaken: Faulensee, Leissigen, and Därligen.