Fisherman

You are a. ranger specialized on the art of fishing. You know every lake, you know every fish, and you know the spells to water.

Fish Master

As a Fisherman, you know better than anyone the fishes, and you can control them.

Cardumen Maser

You can control grouos of fish. Once per long rest, as an action, you can summon a fish cardumen, that counts as a swarm. It covers a 5 feet long cube. It deals 1d10 damage. You can also use this action to perform one of the following things

• Collective attack. You select 4 persons and you can all attack in this turn
• Collective knowledge. You can make everyone of the party your checks of wisdom or intelligence, as well as skills your ar proficient with. You take the average of the results and use as yours. 
• Collective movement. You can grant all your party the same speed or immunity to difficult terrain.

Seahorse Master

As Seahorse master, you can summon, using 2 spell slots, a giant seahorse that has half your stats and a swimming speed equal to your speed. In combat, you can use one of the following abilities. You can't use this ability again until you finish a long rest.

• Bubbles. Ranged weapon attack, 10 ft cone. You deal 1d6 cold damage to a creature you can see.
• Monogami. As long as you have charmed someone, you can't be charmed.
• Disguise. You immediately success a stealth check.  

Shark Master

In combat, you can use an action and 2 spell slots to summon a Shark (I know this is very situational, there is more). You can control the shark as a bonus action. Also, you get the ability to, once per rest, use a shark ability (you don't need to summon the shark in order to do this) Chose one of the following options to make a shark attack. (You do not bite or do the things, you do like a magical ilussion that makes it for you)

• Bite. melee weapon attack. 1d6 cold damage, the target must succeed a strength saving throw or become grappled. 
• Splash. Ranged weapon attack 10 ft range. You deal 1d6 cold damage and the target must succeed a dexterity saving throw or fall prone.
• Charge. melee weapon attack. You deal 2d4 damage in a direction. 

One with the fish

You gain the ability to transformm into fish. If you are a Shark Master, you turn into it, If you are a Seahorse master, you transform into a seahorse, and if you are a cardumen master, well, you turn into that. When using this form, you have the stat block of that animal, and can perform the fish master abilitys as normal actions.

Lord of water

As an action, and once per 2 long rest, you can perform one of the following acts

• Tsunami. Melee weapon attack. Area damage. You create an immense wave that hits creatures in the 10 ft range. Deals 1d10 bludgeoning damage and 1d6 cold damage.
• Current. Melee weapon attack. You push a creature of your choice that you can see 10 ft, and deal 1d6 bludgeoning damage. 
• Drowning. Melee weapon attack. You select a creature you can see is surrounded with water. The creature is grappled, and receives 1d6 bludgeoning damage each turn it starts there. They can do a Saving Throw DC= You ranger level+you strength modifier+your wisdom modifier. On a success, the creature is free. On a fail, the creature is incapacited. You can hold this ability for a duration equal to the saving throws DC. If the creature can't hold it's breath any longer, it dies. While holding this, you can't perform any other actions, reactions or bonus actions, and can't do oporttunity attacks. 

Fisher

Whenever you make long rest close to a body of water, you can spend 1 hour to catch fish. You must use 2 pieces of gold (that's for the bait and those things). You can also use this ability to communicate to animals without needing a spell slot,  or to explore a body of water that's no larger than miles= half your level (minimum of 1) rounded up.