Ovation of the Seas was moored in Tauranga and some passengers were on a White Island shore excursion when the volcano erupted at about 2.11pm local time (1.11am GMT).
About 50 people in total were on the island when the eruption happened. New Zealand Police have confirmed two were British women.
There were also 24 people from Australia, two from China, four from Germany, one from Malaysia, five from New Zealand and nine from the US.
