Sea Base 4

Sea Base 4 was a sea base in the ocean on planet Earth. It was active in 2084 as part of Sea Base Command. It had several weapons systems including energy tracers.

Staff included Solow, Vorshak, Nilson, Bulic, Maddox, Preston, and Karina.

In 2084, Sea Base 4 was involved in a conflict with the Sea Devils and the Silurians. The Sea Devils and Silurians were killed by hexachromite gas released by the Fifth Doctor. As Turlough explained, "They're all dead, you know." (TV: Warriors of the Deep)

Behind the scenes
In The Doctor: His Lives and Times, a Breaking News tweet reports "Minister for Peace says world war is now 'inevitable' following discovery of wrecked Sea Base 'full of corpses'."

In the novelisation of Warriors of the Deep, it was mentioned there were several human survivors, including Bulic, scattered around the base.