So, you’re on a rock, in the middle of the South Pacific?
Seek shelter, from a ballistic missile attack?
Where, under the covers?
During the cold war there were actual shelters there, and everywhere. Really smart people decided they were not needed. From an article I read Hawaii is trying to redo their system since NK keeps threatening them.
Some areas of Hawaii have tunnels where volcanic lava has run out of a lava flow and left a tunnel. Some are quite large and might make good emergency shelters.