And it dawns on me that “You’ll have to excuse them. They’re idiots.” would have worked for Skylynx and Dark Steel just as well as it did for Aria and Sonata.

@Roy-of-Asturia  
Beast Machines had Hammerstrike.
 
Beast Wars actually had two versions of Cybershark, as well as a micro playset that turned into an orca, by the name of Orcanoch, and a happy meal toy Predacon Manta Ray (both name and alt mode, kinda uncreative). And the other crabformer was Razorclaw, just so you know. there’s also two versions of Spittor if you count frogs as aquatic beasts.
 
As for RIDv2, I haven’t seen any signs that they even plan to bring the Predacons back for it, which kinda disappoints me.

@Scrounge  
>Beast Wars Maximal Depth Charge, and Cyber-shark, and Predacon Rampage the Transmetal crabformer, and another crabformer, and Claw Jaw (or Scuba) the squidformer  
>G1 Seacons, also repainted white, but rare (and Japan-only)  
>That violet Autobot Swordbot Shinobi member, his name is Sensuimaru (in pure katakana, no English name equivalent to keep him exclusive to TakaraTomy markets). In the show, he generates his own aquatic dimension field which passes through solid objects, because you know of his alt mode. And his abilities incorporate the element of Water. Arguably the first aquatic Transformer in the current Aligned continuity (on the side of Japan).  
 
 
Judge it for all I care, but at least this Deluxe class-sized toy showed something.
 
That Transfomers Go! toyline and mini-series are rather intriguing, but decent, if one has a taste for combiners, but themed (and anything else from Japan). I think Youtube subscriber walruslaw has all the 10 short episodes. Watched them all firsthand, no subs, despite their own problems.
 
 
TF RID2015: Hasbro must have mentioned the name Depth Charge in one of the articles. So, a higher chance to expect a shipformer, since the TF Prime, while a great show in its own right, had cars and trucks and planes and a motorbike and a tank. And bugs. And not much else. Don’t know if the upcoming cartoon will showcase sea or underwater battles, and even battles in outer space. I hope either company will announce an update to the Seacons (for the Predacon faction).

Given that the Dazzlings seem to release/project the seahorse monsters, I’m not sure this is a perfect analogy, but I don’t have a better one, so whatevs I guess.
 
@Background Pony #18BE  
There’s the Seacons, there’s a sprinkling of them through the Beast Era, and there’s a few here and there through G1, but how many exactly depends on how you count certain things. In the past ten years, though, they’ve been especially scarce: Stateside, all we got is Generations Sky-Byte, and Japan got the one guy on the Swordbot Shinobi team whose name I can’t remember and a couple of Arms Microns.

NO!!! Aria is mine!Eye twitches.

@Roy-of-Asturia  
Sadly aquatic beast modes are rather rare.

Hasbro, TakaraTomy, have the aquatic Aligned Predacons been made yet?
 
OP here posted this horrible excuse of a meme for nought.

I find it ironic that The Predacons and The Dazzlings have somewhat the same color scheme.

@Background Pony #602C we do have keplies though in mlp. they are not exactly killer beasts but they are large sea serpent like creatures with a powerful magical voice.  
from what i am seeing here they looke like windigos mixed with fish like characteristics and have similar powers, yet also the abilities of the kelpie.
 
speculation abounds. though my personal one is that they were originally kelpies. they found those rubies, which can absorb negative emotion and energy, and use them in combination of theri own voices to influence dark emotion to feed on.  
some point they merged with the gems. as seen here. when they were thrown into the human world, they reverted into a weaker state and seperated from the gems.
 
the gems give them powers in the human world. without them they will not have those powers though and, likely, the absorbtion of negative emotion. however it seems plausible if they made it back to equestria they would regain theri singing at least.

mix between siren and horse, basically a horse that lures you to a wet grave, i believe mythology has something like that… kelpie, i think.

@Background Pony #B7BE  
What a shock.

Wow, they aren’t quite as cute as horse… siren… creature… things…