Rogues who take their training aboard navy vessels or pirate ships find themselves taken to the route of the Corsair. The corsair knows that it doesn't matter where you are, you can and likely will be attacked. They can fight in many environments and positions efficiently and have learned to rely less on the help of others.

Upper Ground

Starting at 3rd level, you have a natural inclination towards heights, and more specifically heights above others. If you are at least 10 feet above a creature you may attempt to hide from that creature.

Slippery

Beginning at 9th level, whenever you take the disengage action you can freely move through any creatures space without becoming impeded. In addition, you have advantage on saving throws against effects that would grapple or restrain you.

Lingering Observer

Starting at 13th level, you are able to gain knowledge or information from just being able to observe another creature's actions. If you are able to see a creature's mouth moving you can understand what they are saying if you know the language that they are speaking. In addition, if you spend 1 minute observing a creature and doing nothing else, you gain knowledge of their behaviour and situational awareness. The creature has disadvantage on Wisdom (Perception) checks against your Dexterity (Stealth) checks as you know best how to hide from their view.

Seize the Moment

When you reach 17th level, you can identify an opportunity when you see one. At the beginning of your turn, you can choose to take advantage of the current battle state and seize the moment. If you choose to seize the moment you gain a second action that can only be used as the attack action on that turn. In addition to this, you are limited to using sneak attack twice, instead of once, on this turn. Once you use this feature you can't use it again until after a short or long rest.