The Alps 2 Ocean Cycle Trail is one of the longest in NZ, spanning over 300km from Mt Cook to Oamaru. However you don't need to do the whole trail to enjoy some of the more scenic parts. The stretch along Lake Pukaki is readily accessible from Tekapo - Twizel highway at either the west or east end of the lake. The wide, smooth track gently undulates up and down winding along the shore above the lake. We parked on Haymans Rd (waypoint 1) near where its joins the Twizel-Tekapo road. From there it is about 8km to the spillway at the west end of the lake. The cache is a camo pill bottle type. Bring your own pen.
If you are not cycling, you can access the cache from the road. However take extreme care stopping as there is not much room to pull off the road, and traffic along here often travels quite fast and drivers might be looking at the stunning view, not the road!