The group of Canadian and Chinese family and friends were in New Zealand to attend a wedding, police spokeswoman Vivien Pullar said.
They left Queenstown on Tuesday morning to visit Milford Sound and took a side road to take photos when their van appeared to clip the edge of a single-lane bridge and crashed into the Mataura River, she said.
She said the driver was from Toronto, but police did not immediately release his name.
The driver's 52-year-old wife suffered neck injuries and four others, including the couple's two children, were also admitted to nearby hospitals before later being released, Pullar said. The four other passengers were treated for minor injuries at the scene.
Some of the group was from Hong Kong, Pullar said.
The van crashed about 110 kilometres north of the town of Invercargill on New Zealand's South Island.