As we follow the path of the ancient ice, the boat slows and draws close to the cliffs for an encounter with fur seals and a view of the comical waddle of a Fiordland crested penguin.
The Lady of the Sounds pulls even closer to one waterfall and the more inquisitive among our group quickly need a towel.
Before we know it, we have reached the sound's exit to the Tasman Sea, where Captain James Cook twice sailed past, oblivious to the existence of Milford Sound due to its narrow entry point.
After a short ride back up the sound, we disembark at the Discovery Centre to experience its underwater observatory, 10m below the surface. Here baskets growing black coral, usually found only at much greater depths, attract an array of fish, sea stars and sometimes seals.
Tearing ourselves away from the 360-degree expanse of windows, we ascend the spiral staircase to check out our kayaks and, after a safety briefing, head out into the sound.
The kayaks are almost impossible to tip - even when a certain writer is almost washed on to a beach while taking a photo - so having previous experience is not an issue.
Our one-hour paddle takes us around Harrison Cove, which affords dramatic views up Harrison Valley to the Pembroke Glacier.
After flying, cruising and admiring the sound from underwater, exploring it under your own steam is rewarding and the grand scale of the towering mountains is awe-inspiring.
If he saw the sound from this perspective, even Rudyard Kipling - who described the sound as the "eighth wonder of the world" - might have been lost for words.
CHECKLIST
Southern Discoveries' kayaking combo: Includes a cruise, Discovery Centre visit and one-hour kayak and starts from $169 per person. The flight-inclusive package from Queenstown costs $585 per person.
Joe Dodgshun travelled as a guest of Glenorchy Air and Southern Discoveries.