Diagram of the Ocean Ranger and location of the ballast control room (3)
On the night of the disaster, a severe storm pounded the rig with hurricane-force winds and 15-metre high waves. Seawater broke through a porthole in the ballast control room and damaged equipment.
1 – Draupner wave height for comparison. (Detected on 1 January 1995, the Draupner wave was the first rogue wave ever measured – it had a maximum wave height of 25.6 metres.)
2 - Ballast control room's level above the sea (8.5 m)
3 - Location of the room itself

By Anynobody (Own work) [GFDL (www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0-2.5-2.0-1.0 (www.creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons.