The Monkey Sub is a versatile and accurate water-based tower that is capable of supporting other towers. Each of its upgrades are relevant for all stages of the game. Its early-game is quite strong, with a variety of efficient lower-tier upgrades and crosspaths. Top and middle path are mostly support-oriented, the latter for auxillary damage, and bottom path are highly synergetic with buffs.
Base Sub is a moderately cheap base tower with homing darts that are effective for cleanup, and catching a few faster bloons if set on Strong. When combined with Dart or Sniper, the Sub is a staple in many CHIMPS maps with water.
Advanced Intel allows darts to consistently shoot darts towards the range of other towers.
2-0-1 and 2-0-2 are usually preferred over 2-1-0 and 2-2-0, except versus early Leads.
Twin Guns, while less cost-efficient than another base Sub, transitions easily into Airburst Darts, particularly for CHIMPS.
0-1-1 is decent for accurate high pierce, but may struggle against sustained Yellows and Pinks.
Airburst Darts has a powerful early-game, thanks to its airbursts cleaning up stray bloons and breaking up stronger bloons such as Yellows, Pinks, and Blacks/Whites.
0-0-2 is cheap and is sufficient if the airbursts are needed right away.
2-0-2 is the preferred crosspath, which targets bloons at any tower's range, in addition to Camos if the towers detect Camo.
First Strike Capability does a lot of single-target damage at a long cooldown. It's mainly bought in advance for Round 100 to destroy the BAD, or for quick Timed Boss kills against Bloonarius or Vortex.
Nautic Siege Core excels against both Bosses and deep Freeplay. Its direct damage is above average for the Paragons, though submerging is more valuable if not needing the cruise missile attack.
Submerge if needing faster ability cooldowns, improved hero DPS, and extra damage for nearby Subs.
Time the Final Strike carefully, as it has a very long deployment time. Versus Bosses in Boss Events, it's beneficial to time it a few seconds before the Boss actually enters.
Bosses take 3 seconds to enter; ideally, the timer should reach about 4 by the end of the round.
These all benefit its early-game strength. For the latter, this additionally improves its damage to early MOABs, and later on for single-target damage in general (e.g. Boss Bloon Events). For Half Cash, the large discount to the first Military Monkey allows Dart + Sub to be a strong starting combo when combined with Bonus Monkey!.
The extra attack speed on Last increases overall DPS if there are few targets on screen. Certain map formats (e.g. Flooded Valley's entrances) may require Last targeting regardless.
In the absence of nearby other Paragons, high-damage heroes, or time and money to spam nearby 2-0-4 Armor Piercing Darts, unsubmerged Nautic Siege Core for main Boss damage may be necessary. If using Nautic Siege Core for main Boss damage, rather than support, this speed buff will allow it to take down Bosses quicker.
This section is incomplete. You can help out by expanding it. The editor who added this notice elaborates: Elaborate how to use nautic in each boss and in general. Oh and also this section is designed to provide tips specific to this tower as to how to use it against Bosses, both generally against bosses and versus specific bosses
Boss
Strategy
All Bosses
Subs have decent damage across long distances, have upgrades that have a strong burst of single-target damage, and have great support through Energizer's ability cooldown reductions and Nautic Siege Core's exclusive buffs.
Naval Upgrades, 
Military Conscription, 
Quad Burst
Bonus Monkey!.
Sub Admiral
Flanking Maneuvers
Paragon of Power
