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 $425 on Easy, $500 on Medium, $540 on Hard, and $600 on Impoppable.
In certain spots on certain maps, Submerge and Support can decamo all bloons throughout the game.
Note that the Bloontonium Reactor can reveal camo bloons more reliably and deal damage to them.
In a pinch, it is possible to unsubmerge the sub to use its main attack.
This is the main use for crosspathing the sub as crosspathing does nothing to the decamo effect.
As of Version 18.0, Path 3 upgrades are more favourable as it increases pulse rate.
Constantly changing the targeting option between Submerge and another one seems to make the Sub decamo faster. (?)
Beware of Round 100 if Submerge and Support is your only decamo as the DDTs can spawn in an unfavourable spot for the Sub.
The Submerge and Support is a good option to start of a game of 2 MegaPops. After setting up your defense, submerge the sub to reveal camo while not stealing pops and unsubmerge to attack when needed.
For most cases, it is better off going for 3-0-2 rather than 3-2-0, as the Path 2 crosspaths are useless for the sonar attack. However, it is usually adequate just to stick with 3-0-0 unless it is for decamoing bloons faster once it becomes necessary, particularly against faster camo bloons.