The Schaads have placed a bed at the entrance so geologists can have a lie down to recover from the shock of seeing the supposedly impossible.
Mr Schaad said the vote reflected the quality of the experience at Wairere Boulders.
He and his wife personalised it for visitors, talking to them about the valley's history, geology or discovery, depending on their interests.
Many visitors were as impressed by the work the couple had put in to building the many trails and bridges as they were by the boulders.
"It's hard to get here, but once people are here they just rave about it," Mr Schaad said.
Another factor which helped the boulders reach 16th place was the couple's use of social media. They did not have money for big advertising campaigns but they could put time into Facebook and emails, urging visitors and supporters to vote.
Sixty per cent of their visitors had heard about the boulders though word of mouth, Mr Schaad said.
One of the greatest attractions at Wairere is the Schaads themselves and their tales of how they bought the land without knowing what wonders were hidden there, until a goat helped them unlock its secrets.
If you want to know the rest of the story, you'll have to ask them.
About 283,000 votes were cast for more than 1600 attractions with Hamner Springs taking the number one spot, followed by Rotorua's Polynesian Spa, Akaroa Harbour Nature Cruises, Heliview Taranaki and the Otago Central Rail Trail. Womad in New Plymouth was the top event; pineapple lumps and pavlova also made it onto the 2012 must-do list.
The vote was last held in 2006.
NORTHLAND'S TOP SPOTS
16 Wairere Boulders, Horeke
18 Cape Reinga
19 Bay of Islands
23 Ninety Mile Beach
26 Waipoua Forest
38 Matapouri Bay
48 Tutukaka/Poor Knights
78 Glenbervie Adventure Forest
81 Karikari Peninsula