When brother and sister Nathan and Rachel Cox saw a huge dorsal fin surface near their 4-metre kayak in Houhora Harbour on Tuesday evening, their first through was ''great white shark''.
But their concern quickly turned to excitement when they saw the marine mammal's blowhole and realised they were instead surrounded by a curious pod of orca.
And to add to the thrill, the pod contained several calves who were learning how to catch stingrays - one of an orca's favourite meals.
The pair set off from Pukenui about 4pm on Tuesday and about 15 minutes later, while about half way across, they spotted the dorsal fin ominously moving towards them.
''A huge fin come up beside us and my first thought was a great white shark. Then I saw the blowhole and realised it was orca - amazing.'' Nathan said.
''There were about 15 of them, with only three big adults, and there were lots of calves there, playing with stingrays. Trying to throw them up into the air and bashing them on the water, but it was a bit too shallow there and they weren't having much success.
''It was a very special experience for us.''
Nathan has seen orca several times in the harbour - including once when they came up to the Pukenui Wharf when he was standing on it - but this was the first time he'd seen them feeding on stingray up closely. The orca were on the harbour for about three hours, but he and Rachel only had an hour or so with them before they ran out of space on their camera.
He said he accidentally hit one of the largest orca with his paddle.
''I was trying to push off and this huge orca came up at the same time and I accidentally struck him. He just gave me a shower from his blowhole - it didn't seem to bother him,''
Nathan said the size of the orca - he reckoned one was almost double the length of their kayak - was awe inspiring and made them realise just how ''very, very small'' we humans are.
''It was also pretty intimidating when the big fellah came right up beside the kayak - it was huge.''
Nathan said Rachel loved the experience - once her initial apprehension at thinking it may be a shark vanished it turned into pure happiness.
''It was just an amazing, overwhelming experience for both of us.''
This is the time of year when orca and dolphins are regularly seen along Northland's 2700km of coastline.