I have just spent 3 days in Lake Sumner Park with a group of 5. We spent 2 nights at the Jollie Brook hut, the tramp in is an easy 4 hours along the Jollie Brook. It involves a lot of crossings, so wet feet most of the time. The track begins at a swingbridge across the Hurunui River on the Lake Sumner Road. Our middle day there was spent climbing the ridge behind the hut. We set out to go towards the summit of Jollie Brook, just over 1500m, we reached a point at 1193m and decided to follow another ridge down to a scree that we had noticed going in. It was a bit tricky getting onto but once on it the ride down was quick but well worth it.
The last day was spent tramping out over the gentle and pretty Gabriel Saddle to the Gabriel Hut. We went from there to Lake Sumner and the outlet of the lower Hurunui River. From the hut back to the bridge is along open river flats so is easy going.
This is a good trip for anyone wanting an easy and scenic trip away.