This week's puzzle is all about being a bit of a detective. No nasty bearings ;-), just distances and a story.
Be super careful of the map that you use - you can do it on either the Harvey British Mountain Map South Snowdonia, or you'll ned Ordnance Survey OL 18 and 23.
Have a really close look at when your map was printed. From left to right beneath is the Harvey Map, then the Feb 2019 edition of OL23 and then to the right the previous edition (April 2013) of the OL23. Local knowledge says that the lake at Trawscoed was built in the late 1980's.
So, be prepared to don your favourite detective coat, and really get into the map details.
It might help to really have a look at the legend that applies to the map you're using. Both Harvey Maps and Ordnance Survey helpfully supply these in PDF for you to use. Here are the downloads:
Harvey Maps - https://www.harveymaps.co.uk/acatalog/BM_legend.pdf
Some will be easier to find on one map or the other, but the descriptions beneath use mainly the OS legend descriptions.
Start - SH 7233 2687
Less than 1 km approximately North there is a milestone.
From here, go East and join the National Cycle Network trail 82 heading North.
At the road generally less than 4m wide turn North, still on NCN 82 until you reach a place of worship.
From here, go East less than 1 km to a non-roman archaeological site.
Just south of East, and just over a kilometer away is an enclosed area of land with no access rights, follow the track leaving initially south west back to a road generally less than 4m wide.
Now turn South East and cross 3 cattle grids. Turn immediately north on the public footpath.
Where this joins a road generally less than 4m wide, turn uphill to leave the wooded area before heading downhill. Go steely down a piece of road (between 1 in 7 and 1 in 5) to a river crossing. Continue East until a public bridleway forks to the left.
After 2 fords cross a saddle at an altitude of 420m before forking right on a track.
Where the track is no longer a public right of way (close to Trawscoed lake) follow the right of way over 2 foot bridges.
Just before joining a minor road, follow the most southerly footpath South.
After crossing a ford, cross 3 field boundaries before meeting a place that four Public Footpaths cross.
Follow the path approximately 750m downhill.
At the minor road, turn west. After approximately 400m you should be able to call for a taxi....
But, what is the name of the river at this point?