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Diamond in the Rough, Tasman

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Diamond in the RoughIntermediate

Submitted by Steve Beatson

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Trail Information





Tasman and Nelson


Front country - easily accessible


Undulating, some big hills

Native bush
Open tussock/grasslands
Open ridges/tops


7:00 (Slow)
5:30 (Moderate)
4:00 (Fast)



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A great run in a beautiful part of the country, this run has a mix of easy trail to no trail, mostly runnable, bush and tops and lakes.

From the Cobb Reservoir take the Sylvester Hut track to Sylvester Hut (5.5km and 1 hour). Wide runnable track, gaining 450m over 4km so take your time.

From Sylvester Hut take the track to Lake Sylvester, then on to Little Lake Sylvester and Iron Lake (3km past the hut). By the time you get to Iron Lake the track is fading out, but still easy to follow.

From Iron Lake, pick your way up to the top of Iron Hill following cairns to the summit. You could sidle around to the right a bit before the summit, although missing out on great views further up the Cobb Valley and bagging a peak. Lake Lockett can be viewed to the NW from Iron Hill.

Follow the ridgeline off Iron Hill to the NW (better than dropping off the ridge too soon as on the map) until it's easy to drop down to the outlet to Lake Lillie. Sidle around from Lake Lillie above the bush until above Diamond Lake, then drop down through the bush to the lake. Don't drop down too soon, to avoid coming out below the lake - if unsure follow the edge of the bush around to the top of Diamond Lake, then follow the shoreline.

This is the section of untracked route done (4km from Iron Lake to Diamond Lake). From Diamond Lake pick up a trapline that goes to Lake Lockett and all the way back to almost the end of the run. The trapline has been formed into a technical single track that is runnable in many parts and is marked with red tin lids and triangles, not the standard DOC orange triangles.

At Diamond Lake look out for the first marker on the true left 10-20m below the lake outlet. From here it is well marked and generally easy to follow.

Lake Lockett is another highlight, and well worth deviating the 200m or so from the trapline (at a small tarn) to visit. After returning to the small tarn, make sure you follow the markers to the left (not right back to Diamond Lake).

Continue to follow the trapline for approximately 3.5km where you will cross Diamond Stream onto the true right. After another 3km the trapline comes out at an old quarry where a 4WD track takes you down the last 1.5km to the Sylvester Hut carpark.

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Features of interest

Seven stunning lakes. Iron Lake, Diamond Lake and Lake Lockett being particular highlights with great camping spots to tempt you back and explore further.

Make Up of Run

Untracked / Route only: 20%

Technical Single Track: 35%

Moderate Single Track: 10%

Easy Single Track: 20%

Farm Road / 4WD Track: 15%

Route Data


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Overlapping Runs

The following trails overlap with this run to some degree. You may wish to combine them but please note that to qualify for FKTs on these runs you should record a separate Strava activity for each

Sylvester Hut

Sylvester Hut

Length: 10.00km


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  • Access

    Sylvester Hut Track at base of Cobb Reservoir - approximately 50km from Takaka, via Upper Takaka. If travelling from Nelson, travel over the Takaka Hill to Upper Takaka. At Upper Takaka turn onto Cobb Valley Road. From here it is 30km to the Reservoir. It's a stunning drive but slow - allow a good hour. Tar sealed to the power station and gravel from there.

    Space for 12+ cars and plenty more back towards the reservoir.

    49 km

    72 minutes



  • Staying Safe


    As for any alpine trail, only attempt in good weather.
    Sidling around from Iron Lake can be a bit tricky, easier to navigate by going up Iron Hill (bagging a peak in the process).
    When approaching Diamond Lake, don't drop down through bush too soon as you will come out below the lake. If in doubt, follow bush around bringing you to the top of the lake.
    From Diamond Lake route follows a trapline - red triangles / round tins are used not the standard DOC orange triangles. Look for the first marker 10-20m below the outlet to Diamond Lake on the true left. This trapline is maintained by a bunch of keen and generous volunteers who are happy for people to use at their own risk.

    Very patchy.

    Thermal leggings, Long-sleeved thermal top, Seam-sealed waterproof jacket, Gloves, Beanie/thermal headwear, Personal Locator Beacon (PLB), Whistle, First aid kit, Extra food for emergencies, Survival bag, Cellphone, Compass, Map, Crampons / microspikes (for winter conditions).

    No shortage of water. Unlikely to be issues drinking from any of the lakes or streams.

    It can snow every month of the year in the Cobb, so always be prepared and check the forecast. Iron Hill and surrounds will have snow in winter and Iron Lake can freeze over - it gets cold up there!

  • Post run indulgence

    Roots Bar
    Takaka, Golden Bay
    Great food and drink. Often live music

    Mussel Inn
    Onekaka, Golden Bay
    World famous - thanks to Lonely Planet. Sitting around the fire pit talking about trail running is hard to beat.

  • Sponsor this trail

    If you are interested in learning about sponsorship opportunities, please get in touch below:


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