Atlantans get some support

[Sora1499]

Atlantean Vanguard
{WATER/Level 3/Sea-Serpent/Effect}
When this card is Normal Summoned: You can Special Summon 1 Level 4 or lower "Atlantean" monster from your hand. If this card is sent to the Graveyard to activate a WATER monster's effect: You can Special Summon 1 Level 4 or lower "Atlantean" monster from your Deck, but it cannot be used as Xyz or Synchro material this turn. You can only use this effect of "Atlantean Vanguard" once per turn.
1500/0

Atlantean Swordsman
{WATER/Level 2/Sea-Serpent/Tuner}
If this card is sent to the Graveyard to activate a WATER monster's effect: You can add 1 "Atlantean Palace of Poseidra" from your Deck to your hand.
1200/400

Atlantean King, Neptune
{WATER/Level 5/Sea-Serpent/Synchro/Effect}
1 WATER Tuner + 1 or more WATER non-Tuner monsters
Once per turn: You can send 1 other WATER monster from your hand or field to the Graveyard to target 1 monster your opponent controls; send that target to the Graveyard.
2400/1900

Atlantean Palace of Poseidra
{Spell/Field}
All Level 4 or lower Sea-Serpent-Type monsters you control gain 500 ATK. Once per turn, if a face-up Level 4 or lower Sea-Serpent-Type monster you control would be destroyed by battle, it is not destroyed.

They're cool on their own and shouldn't have to rely on mermails so much.

[Darj]

I'm not an expert on Mermails so I can't tell if these could break them somehow.

 

However, I don't get how the Field would help the deck: the effects are generic and rather underwhelming, and the only Atlantean it directly supports is Marksman so it gets to inflict damage and activate its effect. I really don't see pure Atlantean decks bothering with running this and their searcher.

 

You could improve it by treating it as Umi, or perhaps give it an effect related to the mechanic of using Atlanteans as cost for WATER monster effects. When you do that, Swordsman will become better along with it.

 

A standalone effect for Swordsman would be cool too. But I have no idea of what kind of effect you could give it.