Higher prices for export goods are expected to keep New Zealand's trade surplus at a healthy level over coming months.
Official figures show May's trade surplus was smaller than economists had expected at $605 million compared with April's record of $1.1 billion.
The value of exports rose more than imports, although both recorded strong increases.
BNZ senior economist Craig Ebert says commodities and manufactured goods are fetching good prices and fuelling the export-led recovery.
A one-off rise in the export of pleasure boats in May and higher prices for dairy products and meat contributed to a 10% jump in overall exports.
Mr Ebert says New Zealand boat builders may be snapping up business from competitors in Australia.