Destroy 100 destroyer ships to unlock the Atomic Engine Alpha.

Destroy 100 transport ships to unlock the 2-Hull Crusier.

Destroy 100 aircraft to unlock the 203mm Chain Gun.

When you sink 100 Battleships you get the guided Charged Particle Gun 3. This is a optical weapon with the following stats: Offensive 1300, Weight 600 and price of 59000 and can be mounted on any ship type.

This is unlocked when you sink 500 destroyers.

This is unlocked by sinking 100 subs. This is an auxiliary movement system with the following stats. Top Speed +10%, Rudder response +1, Controlablity +25%, Endurance +500.