New Zealand's South Island day trips: Six of the best

1. ROYAL ALBATROSS SANCTUARY

The clearing of the northern tip of Dunedin's Otago Peninsula for military purposes during World War I inadvertently created the world's only mainland breeding ground for royal albatross. The first chick hatched on Taiaroa Head about a century ago and the colony is now about 250 birds due to conservational vigilance. The sanctuary's guided tours unapologetically mix defensive infrastructure with avian wildlife; the 1.5-hour Taiaroa tour takes you through wartime tunnels to a windowed viewing area just metres from nesting birds, or hatched chicks, depending on the season, and ends at the interactive Armstrong disappearing gun. See albatross.org.nz

2. TE ANAU GLOWWORM CAVES

This experience begins with a boat ride across New Zealand's second biggest lake, Te Anau, in the country's largest national park, Fiordland, within the enormous Te Wahipounamu World Heritage Site. The tour's main attraction, however, is miniscule. After you've docked, had a brief biology lesson and walked into a cave where a stream gushes past in search of daylight you'll then reach calm water, darkness, silence and a dinghy. The Maori word for glowworm translates as lights reflected in water and that's the effect as you float under a low ceiling naturally decorated with thousands of bioluminescent larvae in their preferred habitat. Tours are just over two hours long. See realjourneys.co.nz

3. MILFORD MARINER CRUISE

Sleeping on Milford Sound/Piopiotahi aboard a 700-tonne trading scow replica is so much more than a buoyant bed for the night. Once the Mariner motors from the terminal and moors out in the most northern of Fiordland National Park's glacially-formed inlets, where clifftops are 1200 metres above the high-tide mark in places, there's the offer of kayaking, tender boat cruising and swimming off the stern. The vessel sleeps 60 and dinner is a carvery buffet with a licensed bar and generous desserts table. The evening ends with an entertaining slide show and the next day begins with a Tasman Sea sunrise and more wildlife spotting. See realjourneys.co.nz

4. HAAST JET BOAT SAFARI

Over one or two hours this family-owned and operated company introduces you to the Haast River in Te Tai poutini (the West Coast region). Within fully enclosed vessels you'll be transported at high speed from Haast Bridge to the 30-metre Roaring Billy Falls, where there's ancient rainforest on the banks and the water is tropical blue from suspended Southern Alps glacial till. Stay on board for 360s or watch from the pebbly shore as everyone else gets that out of their system. See haastriver.co.nz

5. TRANZALPINE RAILWAY