(this info is general knowledge to inhabitants of waterworld – no spoilers)
Another source of the income and power of the elves is that you basically can’t get anywhere without ’em. It’s a sea world – very few islands, a couple of major currents, some “cities” are actually floating. But there is a bit of a trick.
The elves have worked out a way of taking a cutting of a tree, a cutting which is “aware” of where the original tree is. A potted cutting can be read via a simple ritual. The few islands almost all have at least one navigation tree, and the elves thereon will sell you a potted cutting. We simply call these “compasses”.
However, after a while they stop being “part of” the tree they come from – and they don’t tend to live long anyway. So a major expense for any long-distance traveller is paying the elves for tree compasses – it’s in effect a tax on all trade. The range varies, too. Any trade ship will tend to have an area near the bridge with half-a-dozen compasses in a gymbal. In smaller ships, the captain tends them. Larger ships have an arbourist/navigator and pay him well (if you can get an elf, then bonus! – but elves almost never go to sea).
So navigating involves moving from navigation tree to navigation tree – which have different ranges, btw – using the winds and currents. Finding a new area means either not starving to death before you stumble over it, or paying someone for a compass and somehow navigating to within its range.
This solves a number of game issues, and creates scope for quests related to navigation. Instead of the world being a featureless blue orb, it’s a set of overlapping discs – the limits at which the various navigation trees can work. Some of which move – trees located on moving platforms in the sea (which tend to be a little smaller than the very few land-based ones). Nature checks, of course, to perform the ritual.
Oh – breaking into other ships at port and attempting to steal their compasses is distressingly common. Pirates will steal ’em too – a ship in open water with no compasses is pretty much fucked.