Things to do and places to go

Picton and Marlborough Sounds

For the more energetic there is Cycling, Kayaking, Hiking etc,

http://www.wildernessguidesnz.com/
http://www.marlboroughsounds.co.nz/
http://www.queencharlottetrack.co.nz/
http://www.qctrack.co.nz/
https://marlboroughnz.com/guides/walks/
https://www.newzealand.com/au/marlborough+walking-and-hiking/
https://www.newzealand.com/au/feature/snout-track/

Combine short walks with a boat cruise

I have been on the E-ko tours boat for Dolphins, and they have some good wildlife tours too,
book before you go there, they are quite popular.
http://www.e-ko.nz/
http://www.e-ko.nz/product/Wildlife-Island-Sanctuary-and-Dolphin-Cruise-(Motuara-Island)

other tour boat operators are http://www.beachcombercruises.co.nz/

Visit museums,

Picton Heritage & Whaling Museum

Discover the fascinating history of the Edwin Fox, the worlds 9th oldest ship.