Stream trek: Ping Nam stream (屏南石澗)

Why it's worth it: 

Duration: 

(~6.2 kilometers) 4 hours if you are not stopping/swimming. 
Trail (bus stop) to stream: 35 minutes. 2.5k
Stream: 2.5 hours. ~700m
From stream end to bus stop: 60 minutes. ~3k

Difficulty: 7/10. Short but you have to be careful when walking on rocks which can be slippery. This cannot really be done as a dry trek (ie. you will get wet). The waterfall-avoiding paths are not as clearly defined as for other streams; there are some ribbons but not always obvious. No need to be a rock climber though.

Cel phone coverage: Pretty much everywhere (trail and stream).

Appreciation: 9/10. Really nice waterfalls. The water is very clear and inviting. Nice spots to lay a towel around the water pools. High density of waterfalls, good water flow. 

Transportation: Take the MTR to Fanling station (about 30 minutes from Mong Kok East). Take KMB bus 78k (if you don't want to have to call the stop) or green minibus 56k (http://hketransport.gov.hk). 25 minutes ride to destination. Get off at 南涌 NAM CHUNG.

It's a loop so, at the end of the trail, same bus back to the Fanling MTR station.

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Get to the Fanling MTR station, exit A2. The KMB 78k stop is just right there.
It's a 25 minutes ride to your stop,  南涌 NAM CHUNG. 

Just off the bus, cross the road and take the first right (Luk Keng road).
From this point, you are about 35 minutes walk away from the stream.

Click to enlarge

A few nice vistas along the way.

After about 15 minutes walk, you'll reach the intersection shown above. There's Wilson Trail section 10 signage pointing to the road to the right. You will take the road on the right.

Keep going straight until you reach the dam.

At the dam (2.5 km from the bus stop), don't try to jump the fence, climb the stairs on the right, then head left at the top, following the railing. Then left again there's a loosely defined footpath going through the bushes, that's where you are going. You will go past the fence and parallel the stream for about 50 meters or so before going down and entering the stream proper. 

The stream is clear of foliage and quite pleasant to trek.
Be careful of slippery rocks if it has been raining recently.

For a big part of the trek, you can just walk on the rocks and in the stream.

Once it gets too steep (or dangerous), bypass the waterfall either on the right or on the left.
Be careful though to come back to the stream early enough or you may miss the next falls.

Hula Skirt Falls (草裙瀑布). Very nice pool, clear water.
One could spend an afternoon there.

Twin Falls (雙瀑). 

If you stay in the stream, you can't miss the end-point; there's a concrete  bridge going over the  stream. That's the  Nam Chung Country Trail. Take it and head right. You will be going back towards the start of the Nam Chung trail, which you went by on your way in.

Another view, just to make it more obvious.

You'll see milestone C2502 right there.

Some nice views along the way. Shenzen at a distance.

Back to the Nam Chung trail head. About 30 minutes of walking and you'll be at the 78k bus stop.