Routeburn River II+(IV,P) Weka Flat to Sylvan bridge, or III+(IV,P) from the bend in river South of point 646m 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 IV-V 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 II+ 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.

It is vital to understand that it only runs at grade II+ in low flows from Weka Flat down, with one easy portage mid run. The portaged section is grade III – IV. We ran the three drops in Nov21 and these were class 3, but needed the perfect flow.

Above Weka Flat the river is a fantastic Grade III run from the 90deg right hand bend in the river, 400m South of point 646m on the topo map. It has an awesome rapid with a 2m drop at its base. (Enter here from Weka Flat, not the Roteburn bridge)

Above the bend the river is class IV-V.

In that respect the trip is written with the thought process of a class II paddler in mind running from Weka Flat down.

At low flows the river is either classic grade II wave train rapids or technical movement, at class II, 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. If you want to hit the class 3 upper section, continue up to the bend below point 646m on the topo .

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.


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 II 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 IV. 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 third to a half of the river bed under the bridge then this is ideal for a low level class II 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 50 ish 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.

3 Trip reports Log your trip

  1. Jeremy Platt says:

    In Feb 2023 after a couple of days of rain, we walked up the Routeburn to Sugarloaf Stream, walked down to the Routeburn River and then walked upstream until hitting the massive waterfall. We were hoping to find some kind of glory rapid below the waterfall, but unfortunately this didn’t present itself, we did find some interesting looking gr 4 with some pretty powerful holes and while tempting, we decided to portage them and put in at the gr 2/3 rapids right at the end. After this we floated down some very scenic gr 2 until we hit the swing bridge. Around the swingbridge was really nice gr3 which then transitioned into grade 4 and then grade 5, which was really bony at our level (water was still running clear). A couple of the team paddled a handful of the easier grade 4 rapids within this nominally grade 5 section, however they were short and with some rough consequences from missing lines. The final section coming into the bend at 646m (described above), was a fun and long gr 3/4. The river after this eased a bunch until we got into the lower canyon, which was spicier than we thought it was going to be! There was a river wide strainer at the end of the gorge in the main flow, so we chose not to run it. Thanks to Swaney for the info above 🙂

    • Date of your trip -202202
    • Estimated/gauge flow -2
    • When did it last rain and how much? -
    • How long did it take to paddle the section described here? -
    • Any new hazards? -
  2. SWANNY says:

    In December 2022 we again paddled the upper section from the 90 degree turn in the River, 300m South of point 646m on the Topo map. The river was at median flow in Spring conditions. The classic 2m drop (around the intersection of the 420m contour and the River) had now changed significantly. A rock which now laid mid stream, made the entry much more technical and required considerably more skill to run at low to median flow. An easy portage however.

    • Date of your trip -3rd December 2022
    • Estimated/gauge flow -
    • When did it last rain and how much? -
    • How long did it take to paddle the section described here? -
    • Any new hazards? -Rock on 2m drop in upper section
  3. 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.

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