Nevesbu b.v. made modifications on OTN's small submarine 'Aurora' (LxWxH: 7.9m x 2.4m x 2.7m). They included a connecting hatch enabling the submerged vessel to connect to tunnel elements to perform work. In addition a strength verification was performed for the battery compartments to ensure the submarine's integrity at a working depth of 300 metres. The submarine is used for the installation and maintenance of a wide variety of submerged systems.