Abyss Bloon

Abyss Bloon is the special boss of the Event Deep Sea Diving. During that event, if you're playing on an aquatic track, it'll sometimes randomly appears in a round between 95 and 105 and overtake that round. Like the Gap Bloon, there'll also be a message to tell you when it comes, and it also has M.O.A.B.-Class properties.

Abyss Bloon
BGM: Desire Drive

Like the other Event Bosses, its first form is fought right on the track where you're currently in. Abyss Bloon only has 1250 HP, moves as fast as a Blue Bloonand has pretty simplistic abilities: But of course, the real fun doesn't just lie there, it NEVER lies there! Once you've defeated the Abyss Bloon, you'll get 20 Scuba Gears and 15 Bubbles, but it'll get serious, turning the track into an underwater one (water bubbles will fill up the screen during the transition), as well as summoning a machine called...
 * Water Shot: Shoots a strong burst of water to a tower, which deals 5 HP damage and can break through 1 AD. It'll also make the tower twice as vulnerable to electrical attacks for 10 seconds
 * Deep Sea Bloons: Calls 150-250 Aqua Bloons and 50-100 Shock Bloons. These bloons will appear on a random aquatic part of the track (but not further than the halfway point).
 * Whirlpool: Creates a whirlpool in an aquatic part of the track. The whirlpool slowly sucks the towers in in a 200 px range. When the tower gets sucked in, it'll get damaged by 1 HP each second until the whirlpool disappears, then it'll get thrown back. It can only suck in biological monkey towers, and lasts 7 seconds.
 * Oceanic Rain: Makes the track rain for 20 seconds.
 * Flood: Makes the track underwater for 15 seconds. During this period, any non-underwater towers will take 1 HP damage every 3 seconds.

Abyss M.A.N.T.A.
 BGM: Summer Night Fantasia

The Abyss M.A.N.T.A. (Monstrous Abomination in the North of The Abyss) is what you'll be really fighting again. This track is just one plain underwater battlefield, but you've got all the Scuba Gears and Bubbles you would need, plus, remember, Monkey Submarines are natively underwater. You can also place towers on where the M.A.N.T.A. seems to be, because it's actually below you, but take note that your towers will be more vulnerable this way. Oh, and the "wings" of the M.A.N.T.A. can actually flap, and its tail can wiggle around.

This also happens to be the first Time Trial Battle, where you can't lose normally, but instead, you must beat it in a given amount of time (if you Fast Forward, the clock will Fast Forward too), and the time limit for this fight is 10 minutes, and it has 7500 HP. Oh, and you must hit the tip of its tail if you want to do any damage. In any case, it has these abilities: So, that's it for the ambiguous manta. Once you destroy its tail tip, each section of the tail will also explode until the tail is completely gone! However, of course, the fun doesn't end here, as the Abyss Bloon descends and the shields rearrange to become a form called...
 * Abyssal Bloons: Its halo will glow brightly like a portal, and 100 Shielded Aqua Bloons will come from there and surround, the tip of the tail to protect it. Shielded Bloons can block pierce from attacks
 * Electrical Field: Its tail tip will charge up and shoots a lightning bolt that can't seemingly hit anyone. However, underwater, the lightning get conducted across the whole screen, damage every towers by 3 HP and also electrifies (basically burn + confuse) them! Yikes!
 * Thorny Tail: Its tail will float up, then shoots some of its spikes (the spikes that are shot are chosen by random) sideways. Each spike has infinite pierce and can damage towers by 5 HP, as well as popping there bubbles. Any tower whose bubble popped will lose 1 HP every 3 seconds underwater if you don't replace their bubbles quickly, and the bubble will be lost even if the spikes doesn't hit the tower directly but does hit the bubble. Then, it'll grow new spikes to replace these spikes. While its tail floats up, any tower that's located above its tail will also lose 5 HP from contact with the tail.
 * Runic Beams: Its wing pieces then float up then each shoots a white laser beam from the tip that has infinite pierce and can damage towers by 8 HP. Any tower located above the shields will still lose 8 HP (since the shields actually charge up with an energy field around it when shooting the lasers), as well as losing a further 5 HP from contact with the shield.

Deep Sound
 BGM: IDENTITY Part I

Okay, let's just get straight to the topic. :P Time limit: 10 minutes, Health: 10000 HP, Target-if-you-want-to-do-any-damage: the Abyss Bloon itself. Abilities: When you've finally defeated the Abyss Bloon, the whole thing will blow up and HURRAH! The battle is seemingly done and you cheer up as the water darkens! Wait a sec... the water DARKENS...?! Uh oh...
 * Runic Beams: Like above
 * Abyssal Bloons: Again, same as above, but this time the Aqua Bloons will protect the Abyss Bloon instead.
 * Deep Calls: These abilities below will call certain sea creatures (yes, actual sea creatures, not bloons) to fight you towers. Some creatures can actually touch your towers, some can't. Some of them are relatively undefeatable, some can actually be killed (to keep the E rating, the creatures will just poof when killed instead of... you know...):
 * Eel Call: Signified by a green wave from the boss. Calls 5 electrical eels to the screen. The eels can't actually touch your towers, but you can still hit them. Each eel has 300 HP, and can emits lightnings that deals 3 HP damage to the whole screen (as for why, see "Electrical Field" above).
 * Whale Call: Signified by a black wave. Calls a whale that's relatively invincible and will damage the whole screen by 10 HP. However, the call takes 10 seconds, and if you can damage the boss by 300 HP in those 10 seconds, the signal will stop and you'll be all right.
 * Dolphin Call: The most clichéd call ever, signified by a blue wave. Calls 4 dolphins. When a dolphin touches a tower, it'll lose 8 HP. A dolphin has 1500 HP.
 * Pufflefish Call: Signified by a yellow wave. Calls 5 pufflefishes which have 500 HP each, but can "blow up" at random times and when blown up will have 10 AD. When it touches a bubble, it can't move further to touch your tower, but if it blows up then it'll pop the bubble and your tower will lose 1 HP every 3 seconds unless you replace the bubble. If it blows up when touching one of your towers, that tower will lose 8 HP.
 * Manta Call: This must be the craziest thing ever... The signal is signified by a white wave. And after 5 seconds, a faint ghost of the Abyss M.A.N.T.A. above will appear on the screen (without the Abyss Bloon) with all of its abilities! The ghost will last for 20 seconds before disappearing.

Deep Sound ~Broken Wing~
 BGM: Black Noise's Theme Song (19xx)

Oooookkkkaaaayy.... for some reasons that thing is still not dead yet and is still standing there like a ghost... how eerie... Will it ever die? Well, it'll die, if you can make it lose its last 1200 HP in ONE SINGLE MINUTE! Yikes! Luckily, it only has one single ability in this form, but it's not a fun one... After you've defeated this form, Abyss Bloon will finally be popped and the machine will explode for good! Phew!
 * Broken Sound: Continuously emits red waves from the Abyss Bloon. When the ability is active (and for Genesis Bloon's sake it's ALWAYS active!), ALL THE ABOVE KINDS OF SEA CREATURE (save the Whale and Manta), Eels, Dolphins, and Pufflefishes will continuously come nonstop! Worse, every 3 seconds all of your towers will lose 1 HP no matter what because of the noise! You really gotta be quick in this phase!

Backstory

 * Abyss Bloon is the Bloon ruler of the deep seas. He's at first a pacific, but grows wearier and wearier of the monkeys over time because of their oil factories that pollute the oceans, and because they keep popping bloons for seemingly no reason (although to be fair, it's E.N.T.I.T.Y. and Apopalypse Bloon who have been setting the stage all along)
 * Then, one day, a certain young girl (Fukumi Mizuki) managed to create the Javelin, a mechanical swordfish-shaped submarine that fascinated Abyss Bloon. Thus, Abyss Bloon decided to wage war on the monkeys in the Deep Sea Diving to,... well,... exact revenge, as well as to check out the Javelin ship and challenges it once he finds it. (Whether he succeeds in it or not depends on whether you bring a Javelin to the battle or not :S)

Trivia

 * The name Deep Sound is based on two things:
 * Firstly, one of the most awesome (and annoying) SHMUP bosses ever, the final boss of 19xx: The War Against Destiny, Black Noise (that black fighter in the clip, it may also be the name of the bomber, or the name of both, I don't really know. Unlike all the other bosses, its name is not shown in the mission briefing screen. In fact, its level doesn't even have any briefing at all. I got that name from the soundtracks). I've also chosen its theme song for the BGM of Deep Sound ~Broken Wing~.
 * Secondly, the encryption program DeepSound, which can hide secret files in your FLAC and WAV audio files, which I'll admit is a very cool function.