There should be about 5-10 islands in a single game (of differing size)
The rest is water.
I can differentiate between deep/shallow water, beach/island, etc. (but that would just be visual niceties)
Units
There can be multiple units on a single tile.
Player ships occupy exactly one tile, regardless of ship or crew size.
Sea monsters move around randomly (through the waters) and attack anything that comes within range. Every time a monster is killed, a new one spawns somewhere.
Computer ships move between docks (trading routes??) or just randomly (??). You can trade with them. You can also destroy them and take their goods/crew - however, if you do so, they will always attack back at full strength.
Resources
Treasures: these don't give you anything immediately. However, collect all treasures, and you win the game.
Goods: you need these to do anything in the game
Gold: buy/trade goods from docks or other players
Wood/Iron/Cloth: for repairing and upgrading
Gun powder: to be able to use weapons
Crew: to do stuff on your boat (more crew means you can do more and do it faster)
Spices: special, exotic resource (??)
Landmarks: exploring a landmark can give you something special, be it negative or positive.
Camps: you can plunder a camp for men and resources, but it can also plunder you (if you don't have enough men exploring).
The game map will have the following components:
Base map
Units
Resources