WHAKATANE, New Zealand — When Phil van Dusschoten retired as a police officer and started a diving business 24 years ago, the next chapter of his life seemed set, steering visitors through the stunning Bay of Plenty to frolic with dolphins and swim around the volcanic White Island.

That life and livelihood have been on pause since an eruption last Monday fired toxic gas and molten rocks into the air and engulfed the island in ash. Eight people died on the island and another eight have since succumbed to their wounds. Two others remain missing.

Now the country is wondering about the economic aftershocks.

“People come to New Zealand because they expect to be challenged like this, to see if you have the nerve to step outside your comfort zone,” Mr. van Dusschoten said. “We hope that doesn’t go away.”

The tragedy has set off an intense debate among New Zealanders about tourism, including whether nature is being wrongly exploited for thrills and whether enough precautions are being taken.