Timaru's strongest suit as a base is the range of South Canterbury day trips accessible within an hour or two.
Geraldine (38km northwest) is a small inland town known for its craft shops, berry farms, and the Giant Jersey — a two-storey woolly jumper that hangs outside a local store and functions as an unofficial regional landmark. It makes a pleasant half-day drive through rolling farmland.
Aoraki/Mount Cook (156km northwest) is the obvious big excursion — New Zealand's highest peak and one of the finest alpine landscapes in the Southern Hemisphere. The road from Timaru climbs through the Mackenzie Basin past Lake Tekapo, which has its own spectacular turquoise colour and the famous Church of the Good Shepherd on its shore. Allow a full day for the round trip; more if you want to walk any of the trails at Mount Cook village.
Oamaru (85km south on SH1) is the town of Steampunk, blue penguins, and extraordinary Oamaru limestone architecture — the Victorian precinct along the harbour is the best-preserved historic streetscape in the South Island. The blue penguin colony at the harbour returns to nest each evening and tickets must be booked in advance in summer. Half a day is enough; a full day covers the penguins as well.
Waitaki Valley (beyond Oamaru, 120km south) has ancient Maori rock art sites, several hydroelectric lakes, and vineyards producing some of New Zealand's best pinot noir and riesling under conditions similar to Alsace.