Previous trip report from 7/20 is awesome so just adding a few additional points to consider:

1) The loop is great but if strapped for time you can just go to the first lookout and head back.

2) If you slightly less strapped for time then I would strongly encourage going back down and heading over to Cape Horn Falls. Especially this time of year they are like a luxury shower of cool water on a hot day :)

3) And if you are somewhere between 1 and 2, then you could hike the top part but then drive down to the landing and hike to the falls from there.

- And of course the entire loop is great, too!

I did the loop and it came out as 6.8 miles with 1,575 feet of gain fwiw

I ran the Cape Horn counterclockwise starting with the upper section then continuing on to the lower section. Signs clarified that the falcon closure ended 7/15/23. Only saw 2 people on an early Thursday morning.

First mile of the upper section and a large chunk of the lower section are overgrown and brushy- but a WTA trail work crew was heading in to work on the lower section when I was on my way out! So the trail should be in better condition soon. 2 small washouts / rough patches on the lower trail between miles 4-5 or so. Just watch your step.

 The only definitive water source I saw which was easy to access was a creek at mile 3.7 into the loop. A small trickle in the lower loop which will probably dry up in August and then a larger stream with a log bridge over it around mile 5– but it’s hard to access being in a steep gully off the trail so you’d have to really want water!

Trail was shaded when I was running (6-7:45am) and temps were cool but there are stretches that clearly will be sunny in the middle of the day.  
The final road stretch went quickly but it is uphill! Look for a small sign on your left indicating the trail and access to the tunnel that goes under Highway 14.
Signage on the trail was pretty clear plus there are a couple of maps posted. Generally if it’s marked as for horses you will miss the views but have better footing. 
Mostly a very runnable trail- just some spots that required walking for me anyway. 

Not too many people on a weekday, bring a hat and sunscreen though.

Left on this hike a little after 9:00. We were the only car in the parking lot on a Tuesday morning. I had read that someone had their vandalized the day before. As always, we left nothing valuable in the car. This is an out and back hike right now as the lower trail is closed for restoration. If you hike the upper trail to the closure of the lower trail, and back, should be 7 1/2 to 8 miles and 1500 feet of elevation gain. Dry conditions, beautiful views of the Columbia River. Several more hikers as we came back but not too crowded. 

This was my first hike here.  A gloriously sunny day despite the blustery, icy weather. I'm glad I took screen shots of the trail description. All the viewpoint/horses/no horses signs kept me re-checking! Mostly, though, the trail was fairly simple to follow. Like others I'd add a caveat about the uphill/downhill (depending on yr route) section of talus. I was following the upper trail and was really glad I had my trusty hiking pole. It'd be easy to slip on the loose rock and sprain an ankle. I also agree that this is not for young kids or anyone with knee issues.

The views of the river and mountains are absolutely stunning, and it was amazing to see the falls being blown about. Gorgeous clumps of iced-over reeds and icicles dangling above a couple of rivulets. The trail had very little ice -- mostly dry with some muddy bits. The last uphill hike on the road seemed longer than 1.2 miles but maybe that's because I'd left the forest trail!