Thanks for all the responses. I took the advice given and hopped aboard the boat and just kept sailing hugging the shores when i spotted black forest and, voila, thar she be. Spotted the bag icon. Now to round up the mats and build a lil teleport hut next door :)

Yeah, I'm just getting ready to fight the fifth boss and still haven't come across the merchant.

He can spawn as far as an island close to the edge of the world, he has multiple locations, and it all depends on which you find first.

Beyond 10 possible locations and only in the Black Forest...

The further north you go the more likely to hit Far North, the more south you go the more likely you are to hit Ashlands.

So your higher probability would be to look more E - W from spawn.

It can be pretty random, I have actually done complete playthroughs without finding one. But that is rare.

he can be hard to find.. on my current seed i had found 2 Bonemass spawns, killed one of them, and started building mountain forts before i found him.. and i had to do a lot of sailing and searching to find him.. but i wasn't going to try to haul silver down a mountain without the belt

He is specific to the Black Forest biome. He has multiple possible spawning locations and once you generate one of them, he will appear at that location and only that one location.

There appears to be a high tendency that at least one of his spawns will appear only a really short distance from one of the Elder spawns, but it is not the case for all seeds.

Also pay close attention to your map and minimap because his icon will automatically appear from quite a large distance away.

Lucky imho

As you are exploring, pay close attention to your full-screen map as a bag icon will appear in his location. As Ren posted, "He can appear in several different places, but will permanently stay in the first place you found him." In the lower left hand corner of your mini-map a bag icon will appear as an alert confirmation to Haldor's determined location.

If the first place Haldor appears on the full-screen map is an inconvenient location, do not get close enough for the bag icon to appear with the mini-map and one can keep looking for 1 of the other 9 possible locations in the Black Forest.

Super Spoiler.. so i tested this on an old world.. then switched everything except trader off then squinted so i didnt see everything.. bingo i was sooo close to him (apparently you need to be within 2km for his icon to show up..Enjoy: https://valheim-map.world/

Have I just been getting lucky? The past 4 random seeds I've played on had a trader spawn on the same island as an Elder summon.

If I remember correctly, there are multiple locations the trader can spawn in but once you get in range of one of those spawns then that becomes the set location.

He spawns in Black Forest. He can appear in several different places, but will permanently stay in the first place you found him. Iirc there is a dev command to reveal his location, as well.

From my experience, the "discovery radius" seems pretty generous. I've always found him from just sailing along coasts.

His icon shows up when you're a good distance away, still in the fog. There's usually, but not always, one in the next island ring out from your start island, but sometimes they can appear almost at the edge of the world. Always in a black forest.