If you are fortunate to have a few days up your sleeve and looking for a great place to explore or just chill out on your tour of NZ then the Marlborough Sounds is a must.  This pristine natural environment is full of spectacular ridges covered with native bush with views from the top that will take your breath away and secluded little bays and beaches, many only accessible by boat.  The peace and tranquility of the Sounds is a great place to really unwind with a great range of accommodation catering for all. For those who like to explore, the Queen Charlotte track from Ship Cove to Anakiwa is certainly worthwhile and very popular with tourists and generally takes 4 days to complete.  The great thing about the Sounds is the flexibility you have in planning your time there.  The water taxi companies will transport your packs (and even kayaks and mountain bikes) and will pick you up or drop you off at your accommodation or preferred destination so that you only have to carry your day pack if you're planning to hike to your next destination.  If you only have one day, then a popular outing is to travel to Resolution Bay and do a three hour gentle hike to Furneaux Lodge in the Endeavour inlet.  The itinerary covered 5 days, spending time on both the Queen Charlotte Sound and the Kenepuru Sound and doing two sections of the track with days in between to relax. You can stay at three places: Punga Cove Resort, Hopewell and Lochmara Lodge and would totally recommend all three places. You can use the water taxi company Beachcomber Cruises - a very reliable service. If you're looking at really experiencing the Sounds, then join Dolphin Watch Ecotours for an awesome wildlife cruise to see dolphins, seals and seabirds before walking on a predator-free bird sanctuary or exploring historic Ship Cove of Capt. Cook fame.  Dolphin Watch Ecotours even has a special tour that lets you swim with dolphins if you're feeling really adventurous!  If you are not confident in planning your own itinerary, then Natural Encounters Guided Walks offer great guided tours along with sea kayaking.  The best website to access all the information you need with links to the water taxi companies and accommodation, yachting and fishing charters etc is The Picton Visitor Information Site or refer to the Lonely Planet Guide to NZ. Best months to travel there would be January to April.