RoWorld Ports, Boats and Sea Routes

Every RoWorld map has water on it, and on some maps water decides the match. Ports cost 250,000 gold, they must sit on a coastal tile, and they unlock everything naval: sea trade routes, amphibious troop transport and the Warship. This guide explains when that investment pays, how to move an army across water, and why a Port is also a warning light aimed at you.

What a Port actually does

A Port is not a gold generator in the way a City is a troop-cap generator. It is a capability unlock. Build one and three things become available:

• Sea trade routes. Ports send out trade ships, and trade ships generate income the way Factory trucks do. A coastal empire earns more than a landlocked one for the simple reason that it has a second trade network.
• Amphibious troop transport. This is the big one. It lets you move troops to land you cannot reach on foot.
• Warships. A Warship is a separate 250,000-gold purchase, and it cannot be built without a Port. A Warship patrols a sea lane, sinks troop transports, fights other warships and can seize an enemy trade ship. One Warship in a narrow strait can block an entire invasion route.

There is a catch that is stated plainly in the build menu: a Port needs a coastal tile. If the button refuses to place, you are not on the coast. On a landlocked start on a continental map, a Port may be a bad investment until you expand to the shore — and by then someone else may hold it.

When to build a Port

Build it early on water maps. On Southeast Asia and Northwest Passage, land routes are long or absent. A Port on your first coastal city is not a sixth-item luxury; it is how you get troops to the next island and how you bring income home. The map list describes what each of the eleven maps does to the shape of a match.

Build it on defence when a coast is exposed. If a human neighbour starts across the water, your shoreline is a front. A Port gives you the option to respond with a boat instead of watching their transports land.

Skip it on landlocked continental starts. If your capital is deep inland on World or Asia, a Port only pays once you reach the coast, and the gold is usually better spent on a second City and a Defense Post first. The economy guide covers why Cities come first: they raise the ceiling on what you can hold.

Build it when the map rewards claiming across water. On maps where a big chunk of unclaimed land sits behind an enemy coastline, a transport is a shortcut to land nobody else is contesting.

How a boat invasion actually works

This is the step that catches new players out, because the targeting is the reverse of what you expect.

1. Right click the nation across the water. The radial action wheel opens with the options you know: Info, Attack, Ally, Boat, Build, Nuke, Donate, Retreat.
2. Choose Boat. You are now in amphibious targeting mode. If you have no Port, this option will not do anything useful.
3. Click the enemy coastline directly. Not the open sea between you, not empty water, and not their capital. The landing point has to be their coast.

Boat invasions work in the opposite direction from land attacks, and that one sentence is the whole difference between a landing and a wasted transport.

Why You Should Send Boats Early | OpenFront.io

Sending boats early

The strategic habit that catches people is timing. Boats travel, and a transport that arrives while the target is defended is a transport that sinks. Sending them early — before the enemy has finished building their own port, their Warship or their shoreline defences — is worth more than sending a larger group later into a prepared coast.

The same logic runs in reverse for defence. If you know an invasion is coming, a single Warship covering your harbour does more than another Defense Post inland, because it attacks the transport before the transport can become a landing.

The video below shows the same rule in the browser version of the game, which shares RoWorld’s ruleset: the open-source project RoWorld is ported from.

The risk of a shoreline

A Port advertises you. Trade ships leaving your harbour are visible to every Warship on the map, and a naval player will treat a busy trade route as a target. Once you own a Port, your coast stops being scenery and becomes a defensive problem.

Practical consequences:

• Guard the harbour. A Warship near your port deters the whole trade lane, not one boat.
• Do not spread your ports. Two ports on opposite coasts doubles the shoreline you have to defend for the same trade income.
• Expect the first attack to be naval. A player who sees you build a Port and nothing else will assume your land borders are soft.

Ports, alliances and war

Alliances stop combat along a land border, and that rule matters at sea too. A neighbouring nation you have allied with is a nation whose coast you do not need to cover with a Warship — which frees that Warship to protect a trade route instead.

The reverse also holds. When you break an alliance you pay for it: for 30 seconds after the traitor banner appears, everyone attacking you suffers roughly half the usual casualties and you lose about 20% of your attack speed. If you have just built a Port and an alliance at the same time, breaking that alliance is how you invite a naval invasion. The alliances guide covers the timing.

Sea routes and the 80% target

Water is not dead space for the win condition. Every tile counts toward the 80% of world control, and on a fragmented map the fastest way to reach it is often to take the islands nobody is defending, then use the Port that is already there to move troops between them.

This is the plan the territory calculator is built for: work out how many tiles you need, then decide whether a transport route reaches them faster than walking around a coastline.

A short naval checklist

• Coastal tile or bust. If the Port will not place, you are not on the coast.
• One Port to start. A second one on the far side of your territory doubles the shoreline you must hold.
• Water maps: Port first. Southeast Asia and Northwest Passage reward an early Port more than any other purchase.
• Land maps: Cities first. A landlocked start earns more from a second City than from a Port you cannot place yet.
• Warship after Port. It is the cheapest way to make an invasion route expensive.
• Target the coastline. Right click, choose Boat, then click the coast itself.