Monkey Sub (Wacky's (archaic) Conception)

The Monkey Sub is a water-based tower that just circles around its base (or travels in figures-of-eight around it. Also, it stops when it hits land. XD Like Meta's tank, you could always set it to stationary path if that's too troublesome.) and fires tacks out of its turrets that pop three bloons each. It has two turrets. Also, it has two additional modes called Surfaced and Submerged. It behaves as stated above in Surfaced mode, but it provides buffs to nearby towers instead of attacking in Submerged mode. (However, 0-0 Subs do ABSOLUTELY NOTHING in Submerged Mode. :S) Cost: $680

Path I

 * High-Power Tacks: Each tack pops ten bloons instead of three. Cost: $385
 * Sonar Systems: Enables the Monkey Sub to detect camo bloons. Also, nearby towers can see them IF the bloon is in their range. (Very similar to the Remocon's Camo Detection upgrade.) Cost: $510
 * Sea Mines: As it moves, the sub deploys spiked balls that explode after 12 bloons hit them. (Blast = pineapple explosion; also deployable in Submerged mode) Cost: $1250
 * Phalanx Sentry: Adds a rapidly-firing sentry gun to the sub. The sentry fires hypersonically and pops two bloons with each shot. Cost: $4250

Path II

 * Manipulator Arms: Adds two bloon-popping claws to the sub. These allow it to hit bloons in Submerged mode. Cost: $385
 * Treasure Hunter: Occasiinally, the sub finds something valuable underwater. (Same thing as the other upgrade that does it, except for the fact that it is every twenty seconds.) Cost: $1250
 * Torpedo Sub: When submerged, the sub fires little missiles that robotech upwards towards the bloons and explode on impact, popping both black and lead bloons. Oh, and it pops three layers of bloon! Cost: $1700
 * M.O.A.B. Wrecker: M.O.A.B. Wrecker Ability: For the next 10 seconds, all torpedoes will do 500 damage to M.O.A.B.-Class Bloons, and pop 25 layers of bloon. Cooldown: 60 seconds Cost: $8500

Trivia

 * I came up with this in seventh grade, so no hating on me for using towers that are already canon!
 * Phalanx Sentry is a reference to the Phalanx Close-In Weapons System.