Me and my friend did that track today with mountainbikes. It was really cool and the view over the lake was worth the way

Follow "k2k" signs to find parking spot by the marine. I turned around after 5 km walking - very boring walk, barely any nice views over the lake, just forest and not even the amazing nz forest. Also muddy and slippery and the mountain bikers doesn't help. IF U HAVE A BIKE THOUGH: GO FOR IT! For walking I wouldn't recommend it