In March 1999 the ROV ASI Mantaro surveyed the flooded Päijänne Tunnel in Finland in uninterrupted sections of 10 km (6.21 miles). This was accomplished using the ROV’s advanced umbillical cable which has a length of 10 km (6.21 miles) and a diameter of just 14 mm (0.55 in). The ROV used a combination of sonar and underwater video to pinpoint the location of a serious collapse in the tunnel, which was responsible for its flooding.