Build a boat and travel on the water!
Boats can be assembled by using a zone-like tool, and to set sail they need a large enough route to the edge of the map.
They are similar to caravans. All can travel on the ocean, but only ships with a low width (10 tiles max?) can travel on rivers. No ships can move on land.
They require two components: one controller and enough propulsion to overcome weight
Your speed will change based on how much spare propulsion you have.
Controllers:
-Control Spot (No Research) Cant use rudders, requires a person controlling it. Its a spot, too.
-Ship's Wheel (Medieval) Can use rudders, requires a person controlling it
-Ship Controller (Industrial) Requires power, requires a person controlling it. Allows use of non-manual propulsion
-AI Controller (Spacer) Requires power, does *not* need a person controlling it. Perfect for all of your cryptosleep water travel. Doesn't need an AI Persona Core.

Propulsion:
-Oars (Neolithic) Requires manual power, weak. Needs water contact.
-Sail (Medieval) Semi-strong. Doesn't need manual power.
-Large Propeller (Industrial) Requires electricity. Quite Strong. Needs water contact at it's back.
-Small Propeller (Industrial) Requires electricity. Decently Strong. Needs water contact at it's back.
-Encased Large Propeller (Industrial) Same as large propeller, but doesn't need water contact as it is built into the floor. A bit more expensive.
-Encased Small Propeller (Industrial) Same as the Encased Large Propeller, but for Small Propellers instead of large ones.

You can set up new colonies on these tiles, and your ship will be in the nearest space it would fit. This also applies to oceans, where the whole map will be deep water.

Events:
Sea Ambush!: One of your ships has been ambushed by another ship. Similar to caravan ambushes, but the ambushes also has a ship. This does mean industrial factions can use mortars, and similar stuff to that.
Floating X: Similar to the land ruins or areas (eg ancient complexes) but on the water.

Factions also gain the ability to create floating bases, similar to their regular bases but, again, on the water.