Submerge targeting option permanently reveals Camo Bloons in its radius.
~ Upgrade description in BTD6
Submerge and Support (sometimes referred as Decamo Sub) is the third upgrade of Path 1 for the Monkey Sub in BTD6. Once purchased, the Monkey Sub will gain a new targeting option "Submerge" and will automatically become submerged. While set on "Submerge" targeting, it cannot attack with darts, but instead it produces a regular no-damage radar attack capable of decamoing Camo Bloons (including DDTs) every 1.5s (1.275s with Twin Guns, 0.956s with Airburst Darts). Unlike Shimmer the radar attack has infinite pierce but is limited to 52 range instead of ~80 range.
It costs $2125 on Easy, $2500 on Medium, $2700 on Hard, and $3000 on Impoppable.