(Copied from proboards forum https://fastestknowntime.proboards.com/thread/263/greenstone-ridge-trai…) On August 14th, 2012, I ran from the Rock Harbor ranger station to the Windigo ranger station in Isle Royale National Park in 6:55:16 (self supported). The exact route was from the Rock Harbor Ranger Station up the Tobin Harbor trail to the Greenstone Ridge trail. I then followed the Greenstone into Windigo then continued to the Windigo ranger station. GPS data for the run can be found at: connect.garmin.com/activity/212578292
The route is, as far as I can tell, identical to that run by Greg and Scott Drum. It is not, as Eric points out, the full Greenstone, so his record stands for that particular route. But the run from Rock Harbor to Windigo (or vice versa) is substantially the same and much simpler logistically than the route Eric ran, so I thought I'd post this for anyone interested.
My time is quite soft, in my opinion. I was running it casually and with quite a bit of extra weight in my pack (bivy & sleeping bag for an overnight stay in Windigo). Talk is cheap, but I think sub-6 would have been very doable with fresher legs and a more focused effort. And I'm nothing close to an elite runner, so I'm willing to bet the right person on the right day could go under 5 hours.
A few tips on the route. There are a lot of ups and downs, but there's not a ton of total vertical gain/loss. The trail is technical in spots but is runnable the whole way. The Windigo side of the island is much less technical than the Rock Harbor side and is also more shaded, so (in my opinion) it's probably easier to start in Rock Harbor. One of the tougher aspects of the trip was that parts of the trail were somewhat overgrown at about knee level. The trail was still easy to follow but the overgrowth made it difficult to see roots, rocks, and other obstacles, so that slowed me down a little. June might be the optimal month for a run across the island, given that the weather would be cooler and the trail less overgrown. There's also no reliable water on the Greenstone Ridge trail, so either carry what you need or bring a filter and plan to drop down to a lake at some point. I carried 2L on my back and two 22oz handhelds, and that was enough for me on a warmish day.
In any case, it's a beautiful run in a beautiful park, and I highly recommend it.