We decided to run the Foss Lakes - Iron Cap loop CCW as the people who had completed it before us had done, based on our experience, we believe this is the best approach. We started our run at 5:47 AM from the Necklace Valley Trailhead. The route starts on the road for a few miles before turning on to the next trail system, meandering our way up to Chetwoot Lake. We passed a good number of backpackers just waking up, or their dogs letting them know that we were passing by (sorry folks!).
During this phase of the run the rain, which had been forecasted for 2 PM, decided to make an early appearance. The weather continued to flirt with us throughout the day, raining on and off until 12:30 PM when it decided to go at it full on, which I will go into more detail on in a bit as it relates to our effort. There were plenty of water sources along the way up, and after Chetwoot we found ourselves on a game path of sorts, going up and down meandering through boulders until we got to the base of the boulder field to Iron Cap. Luckily during the large portion of our traverse and scramble across, roughly mile 12-15, we were able to avoid getting rained on, which helped greatly with the stickiness of the rock. After reaching Iron Cap, around 11 PM, we tried to follow the GPX down, but right at the section where we should have followed the GPX over the "grassy ledge" as described by Jason Oppler, we decided to forge our own route. This ended up being a costly mistake in terms of time, adding a good 30-45 minutes of wandering about trying to figure out how to not get cliffed out. Moral of the story, follow the person who's done the route, especially in that particular zone! Once we made our way down we continued to boulder hop until we reached a game trail right before Tank Lakes. There are so many cairns out there, so it is very easy to find your way once you get through the ridge lines and down through the cliff band after Iron Cap.
Now the weather started to play more of a factor as we descended, the boulder hopping/scree moving continued further than we had anticipated, and as the rains laid into us, the rock got really wet. This made for very slow moving, and a slight route alteration from Jason Oppler's GPX to gain the main trail again, to avoid the steepest sections of rock. Once onto the main trail we tried to cruise as best we could, but the upper section is fairly rocky and root-y, so we picked our way down until the last 3-4 miles. At this point we were able to find a nice flow on the mellow up downs all the way back to the car at Necklace Valley TH. While we comfortably beat the previous time for mixed-gender there was a good amount of time that we could have shaved off our own effort too.
In summation, there was plentiful water throughout the route (just look how many lakes there are), we carried all our own food and gear and general support - Barrett had to use her first aid kit to stop some light finger bleeding. This route is about 2/3 runnable and 1/3 boulder hopping, scrambling, and bush whacking. Cairns on the off trail sections are very clear, so the route finding was not too difficult, except for where we mentioned.
Thanks to those who have run this route before, and for all the beta, it was beautiful and very serene in that middle section. Definitely recommend this route on a non-rainy day, and I highly recommend following Jason Oppler's route GPX for that descent from Iron Cap, staying exactly on line with it, otherwise you will find yourself getting cliffed out, or at least in store for sketchier descent.