Routeburn River (II+/III-) Weka Flat to Sylvan bridge

Another GY gem of a paddle with beautiful crystal blue pools, cool boulder formations and beech lined forest, along with sensational views of the Humboldt Mountain range and Mount Earnslaw.

Thank you to Alan Swann for the information for this trip page.

The Routeburn river has always looked like it fitted into the `too scary` or `too hard` box for the majority of packrafters. It does hold a grade of class 4-5 in the Graham Charles NZ Whitewater guidebook, pg 266.However while scouting this run from the Routeburn bridge down to the Lake Sylvan bridge it was noticed that from Weka Flat it was much more feasible as a classic grade 2+ run. It is short, 2-3km, but very sweet. We headed in the next day after scouting and were blown away with the enjoyment this little section of river gave and contemplated if it was a first packraft descent?

It is vital to understand that it only runs at grade 2+ in low flows from Weka Flat down, with one easy portage mid run. The portaged section looks like grade 4 and does have tree hazards on each of the three drops, which are particularly tricky in low flows. In that respect the trip is written with the thought process of a class 2 paddler in mind.

At low flows the river is either classic grade 2 wave train rapids or technical movement, at class 2, around and through boulder gardens. 

Check river gauge info at the base of this report.


It’s a 30min drive from GY (Glenorchy) to the DOC carpark and campground for the Lake Sylvan tramp, turn right for Sylvan 3km before the start of the Routeburn track and head to the swingbridge.A great place to camp the night before if your not from the area. This is a very popular tramp in the summer months and its often possible to easily hitch there and back from GY.


There are two options to the `put in`at Weka Flat:

The best way is to take a short 2km tramp through bush and over tussock flats along the fishermans track on river right, which follows an obvious path to begin but becomes steeper with denser bush and a less defined track for 10mins while you pass the small gorge, follow the pink markers in the trees as these take the best route. Just as you feel your off route you will see Weka Flat and an easy hike over the flats.

The second and easier route is slightly longer and less scenic, 3km, back along the road and turn right towards the Routeburn start and at the Weka flat sign head down through the bush to the river.

You can `put in` anywhere along Weka Flat, however about 200m upstream of Weka Flat where the river starts to steepen obviously gives the most paddling.


The river has several characters along its track and provides some great lines through the boulders. Check out the pictures below, they speak a thousand words. Scouting rapids for trees is vital in the main rapids, the river is prone to this hazard. There was however one tree that we had to portage over in low flow (check the pics). If in doubt, give it a scout.

Starting at the upper Western end of Weka Flat the river in low flow is tight to begin and flows along the left bank with ease and diverts onto the right bank just below Weka Flat. There are slightly steeper sections with class 2 paddling along this section. Then the river starts to tighten and drops through larger boulders, which makes for some great technical paddling on rock garden rapid through 3 gaps through the boulders.

200m down stream the trees tighten into one mass and the river steepens with the largest rapid running into a stunning pool, then it starts to look more technical with 3 definite drops over the next 200m. These are roughly 1.5m in size and look runnable for a capable team, grade 4 (However as off Dec20 tree hazrds existed on each drop and scouting is required) NOTE this section is however easily portaged on river right and the last rapid can be ran before the gorge.

The river then runs into an easy and beautiful flat gorge but in April20 had a large tree hazard bank to bank which necessitated an easy climb over in low flow.

The rest of the river is then generally easier class 1 or 11 with one main continous rapid a few hundred metres before the bridge.

Exit at the bridge or continue for another 1.5k to the Dart and exit at the confluence and walk across the paddocks directly back to the car. Permission required from Stu Percy at the Routeburn Station to tramp back on this final section.


Visual. At the Lake Sylvan bridge, if the river covers about a half of the river bed under the bridge then this is ideal for a low level class 2 run.If the river is bank to bank it maybe too high but ideal for more experienced paddlers and conversely if you couldn`t paddle downstream from the bridge its maybe too low. If your not sure drive to Weka Flat and have a look downstream from the river bank.

Closest flow gauge: Dart River at Hillocks.

Median flow on the Dart gauge is 45-55 cumec, although it is a different catchment and much bigger it does give some indication to flow levels in the greater GY area. If the Dart is at median flow to 100, there is a good chance the Routeburn flow will be fine. If the Dart is running at 150+ then some caution may be required. At 200+ then its maybe best to wait it out.

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  1. Swanny says:

    In April 2021 we hiked a further 300m upstream past Weka Flat to the 90degree turn in the river, 300m South of point 646m on the Topo map. The river was at low flow in late summer condition. This section to Weka Flat gave some excellent G3+ paddling with some 2m drops and was well worth the additional hike.

    • Date of your trip: 3rd April 2021
    • Estimated/gauge flow: LOW
    • How long did it take to paddle the section described here?: 45mins

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