oh and don't forget about Draining Whelk :)

I never noticed before Draining Whelk has water-themed art, so it's a candidate for sure!

Spreading Seas could be worth playing as well as to get rid of a land someone's abusing plus there's creatures with island walk in here, trololol

oh and True-Name Nemesis would be a strong pick here!

themed cards i've found Sage of Epityr, Keiga, the Tide Star, Cephalid Constable

Spreading Seas is solid, but it didn't do much for me when it was in the deck. Of the others, Cephalid Constable seems super fun and fits both the sea creature and bounce theme. Thanks for following up Mutley2063!

+1 Awesome!

+1 Just built this theme deck, really fun to play. Trench Gorger does a beautiful job in this deck!

Whoa no Quest for Ula's Temple ? :(

Quest for Ula's Temple is rather underwhelming without other cards to set it up like Sensei's Divining Top and Crystal Ball.

I love the theme, Krakens, Leviathens, and all other forms of gigantic sea life make me happy. It reminds me of my Mother Nature's beatdown build that I just got around to posting. A+

Admittedly Ula's temple has gotten me into some tough spots when I scry away valuable bounce for maybe a creature... Thumbs up for being the reason I've had so much fun with my first commander deck :) This deck has been a blast and washing out the board with a Whelming Wave never gets old.

Adding in Oboro, Palace in the Clouds and/or Ghost Town makes for a nice soft-lock with Quicksilver Fountain, as you can just keep bouncing them before the beginning of your turn, and then replaying them. Nice deck! +1

Have you tried running Soldevi Excavations?

Master of Waves would be amazing in a edh mono blue and try Archetype of Imagination basically 6 to make all creatures unblockable granted they could have reach but that is unlikely then try cards to buff flyers like Favorable Winds

You might like Sky Diamond for early ramp. People tend to forget about the diamond cycle since most decks are multicolored.

There's also Grozoth if you want to get more fatties in your hand late game.

Since I haven't replied in a while, here we go:

@TheSlowestBro: Thanks for the tip on those lands, I did put Oboro, Palace in the Clouds in, but have yet to play it with Quicksilver Fountain, oh the hate it will bring!

@fuster: Soldevi Excavations is pretty good, but mana is at a premium in this deck since the creatures are so expensive. If I find I want another scry source, this will be on the short list.

@skull_kid: I've had Master of Waves in the deck, but it was always underwhelming since the tokens usually die if it's removed. I could see it being better with more anthem-type effects. Archetype of Imagination is awesome, but I'm trying to keep the creatures on theme.

@electromancer: I'm usually a fan of the 2CC mana rocks, but they just don't get me far enough ahead. Cards like Mind Stone used to be in the deck, but were later swapped for rocks that produce 2+ mana since I have some high cost cards that require a bit more to cast to keep up with the table. Regarding Grozoth, it was in my initial build, but since it could only tutor a few creatures (2 in the current build) and requires mana to attack it was often a dead draw.

Thanks to everyone for the suggestions!

Bounce sub-theme needs Aether Gale.

Cool

I JUST finished purchasing my version of a Thassa sea monster deck I built myself, and I REALLY wish I had seen this before I did that! You can check it out on my page, but damn, some really cool ideas in here. I'm DEFINITELY going to have to toss a Blade of Selves in here at some point.

+1 Huge fan of your deck! As others have stated, this feels like it embraces the ideals of Commander 100%.

I agree with your comments about the 2cc mana rocks not being enough. Worn Powerstone seems like an omission that would be good, maybe over Sapphire Medallion or Cephalid Constable? The deck looks like it will mostly be casting a single spell per turn, which makes the Medallion less good (because then it acts more like a 2cc mana rock). The Constable seems like it would be better as a burst card draw spell without a way to make it bigger - but that's just my opinion.

As more early game control, might I point you to Aboshan, Cephalid Emperor? On theme, very powerful.

Again, very nice!

I pulled Worn Powerstone for Hedron Archive a little while back, but the more cheap ramp there is, the better. I've also contemplated running Turnabout since it's a flexible spell and could help drop a fatty a few turns early or give it haste with some equipment. I probably won't cut Sapphire Medallion as it's been very handy mid to late game to get a few spells a turn off, or to just be able to hold up one island for a critical counterspell after playing something on curve earlier on. I'll consider Aboshan, Cephalid Emperor as it seems to be rather strong rattlesnake if I keep the mana open.

Thanks for the suggestions justnthrguy!

Glad to see you are running Stormtide Leviathan. That's my favorite blue creature, and it fits your theme.

AEtherize

What do you think about Dissipation Field?

@Mtg_mill: I kind of like AEtherspouts over AEtherize this since commanders will go to the command zone with AEtherspouts. I don't like running too many conditional bounce effects, but maybe I'll just run both!

@Hipparchos: I've run Dissipation Field in other decks and found that people abuse it more often than get abused by it. They'll reuse their ETB creatures, which EDH is full of (or at least my meta), until they're ahead and then kill it. Maybe it would work a bit better in this deck since there's the threat of unblockable dudes coming at them if they waste time reusing value creatures. Something to consider.

Thanks for the suggestions!