The Queen Charlotte Track in the Marlborough Sounds is a truly great introduction to off-road multi-day mountain biking. Best enjoyed in half-day portions so you can spend plenty of time wallowing in the ocean, imbibing the views and the occasional quenching ale.
Cruise the track over three days staying overnight in Punga Cove and Lochmara Bay. You could squeeze it into a weekend by using the camp site a couple of hours beyond Punga Cove which has water and a cooking shelter. Masochists may choose to blitz it in a single day with all the requisite urgency and fatigue that goes with that approach. Anyway here's the three-day version...
Ship Cove to Punga Cove (about 4 to 6 hours of cycling heaven) Catch an early water taxi from Picton to Ship Cove. Travel time is around an hour. Cost is $50-100 (the lesser rate if you charter a boat for a party of five or more) plus a fiver for your bike. Arrange for your overnight gear to be ferried ahead each day to your overnight stop, so you can travel light with just your day pack. The track snakes its way through native bush in and out of the inlets, all the way to Punga Cove. Don't be deterred by the initial slog out of Ship Cove. Backpacker accommodation at Punga Cove Resort is $45 per night (book in advance - there are only 8 beds at this rate). Or you could choose to camp. There's a restaurant at Punga Cove if you don't fancy lugging cookers and food with you.
Punga Cove to Lochmara Bay or Portage (2 to 4 scenic hours) It's a bit of a grunt up and along the ridge before dropping down to Portage. A few years back, the good fairies at DOC created some new benched track along this section which lets you cruise the tops. The foliage is second generation scrub but the views into Queen Charlotte and Kenepuru Sounds compensate. And the downhill into Portage is a snorting good time. Stop here if you're down on energy, otherwise continue for another hour to the idyllic Lochmara Lodge and Restaurant - just off the main track in the bay of the same name. Plan to arrive early in the afternoon to make the most of the grounds and facilities. Rooms are $100-200 for two but worth the indulgence. Portage Resort has less expensive options with bunk rooms at $45 or the nearby campsite in Cowshed Bay.
Lochmara Bay to Anakiwa (2 to 4 hours); Anakiwa to Picton (2 hours) A short easy climb after breakfast reunites you with the main track before scooting down to TeMahia saddle. From the saddle it's benched singletrack carving its way down through the bush to Anakiwa. By the end you'll be wearing a wicked grin and wanting to head back for another whirl. To unwind, it's a scenic amble on the tarmac around Queen Charlotte Drive to Picton.