During Phase 1 boomers can be loaded with warheads if they start in a sea territory next to a home territory and moved to any sea or ocean on the board. If warheads are loaded onto a boomer, they are removed from the Superpower resource centre and placed on the boomer. Once moved onto the boomer they can not be moved back, only fired.
If the territory that they are moved to is owned by the superpower, the boomer may surface and be visible to all players, otherwise it will hide under water. Boomers may move alongside navies for no extra cost in the move and attack phase, but may not move by themselves.
Also, when hidden or visible, and when they have available warheads, boomers may perform short range strategic attacks, called boomer strikes.