You could only do it in late spring, when the stream was not too fierce with snow-melt, but there was enough water to get by.
You'd stay at the West-gate, in those funny little guest rooms they use to have near the Doors, right by the gate-stream, so you could hear the water running all night through the rock.
Then you'd get up early in the morning when the mist was still filling the valley before the walls. As the boats went down the stream, the morning light would come up through the mist and you'd start to see the red rocks and sand and the path, and then as you came out from the shadow of the mountain-walls the green lands would open up either side, full of holly trees and spring grass, and the larks would be singing over the rush of the water. "
inspired by We're Sorry Celebrimbor Month
It's difficult to draw small faces with fat sticks of pastels so I'm not too embarrassed by these, although the dwarf on the second-to-last canoe does rather look as though he's wearing a fake beard (Actually, maybe she's a lady dwarf?). I think Celebrimbor, at the front of the first boat with a paddle, has just made a slightly risque joke to the two lady elves in the front right boat that is rather too close to the shore, hence the slight blush from the elf wearing blue.
Those two lady elves were supporters of Caranthir who were captured and worked as thralls in Angband. They were freed after the War of Wrath, and decided to stay in Middle Earth and then go to Eregion with Celebrimbor rather than to Valinor because of their long friendship with the Dwarves of Belegost. I don't know the backstories for the other Elves, although I think that might be Narvi in the back of Celebrimbor's boat. Like a sensible dwarf, he has chosen to wear a helmet just in case the boat capsizes on the rocks in the Sirannon.
Incidentally, this is a better photo: I'm not sure if that's just that it's easier to photograph pastels, or if my fiddling with settings worked. Unfortunately, I had assumed that all the setting details would be saved in the Exif data of the photo and they weren't. I know I took some photos in portrait and landscape mode though, and also experimented with changing the white balance settings in a number of ways, and this was one where I'd changed the white balance away from the default. Next time I must take notes.