I noticed you have a lot of islandwalk in your deck 4x Lord of Atlantis and 4x Master of the Pearl Trident and was wondering why there aren't any cards to turn an opponent's land into an island/land of choice so the creatures can attack. Islandwalk wouldn't work unless you were then versing someone with blue in their deck. Sadly, not every person runs blue in their decks, and your 8 islandwalk giving creatures wouldn't do much to help the deck win.
Halimar Depths is also one of my favorite blue lands. It comes into play tapped, but it also gives you the same effect of ponder, minus drawing the card right away (but you still get to put them back in any order), and you get mana from it.
I also really love Merrow Commerce as it essentially gives all your merfolk vigilance. You can then keep them untapped and have blockers.
i was gonna sideboard merrow commerce as i too think its certainly something that could be useful in places, but might not be quite enough for a main deck spot. i agree with the making something an island is better than hoping they play blue i think ill be putting in card:Aquitect's Will seems the best one in terms of cost and it also draws me a card
As far as lands go, using just Spreading Seas to turn on island walk is more than enough.