The Puffin is a seaplane gunship that drops homing torpedoes into the water. Being able to circle and strafe ships while dropping each torpedo, makes it more effective in narrow waterways where torpedo bombers tend to have trouble hitting their target.
Use it to take out those pesky submarines without sacrificing your ships.
It’s got higher DPS than its CORTEX counterpart, the Monsoon, but also costs more to produce. Remember to combine them with sonar planes to target underwater units.