Mr Ainsley had gone to rescue two mates who got stuck while driving on the Tautuku Peninsula, in the Catlins.
His vehicle was later found in the sea at the bottom of a 60m-high cliff out on the peninsula about 11.20am on Saturday. His body was in the water nearby.
Daryl Ainsley's brother, Lomas Ainsley, told Stuff it was thought his brother had become disoriented in the dark and gone over a blind spot on the cliff.
He told the Otago Daily Times it was ''typical'' that his brother had died going to help others,
as he was known for his ''big heart'' and helping people out
in any situation.
Lomas Ainsley said the family was overwhelmed by the tributes pouring in for his brother.
Daryl Ainsley, a 52-year-old father of three who grew up in Cromwell, was a respected Cromwell shearing contractor and president of Central Motor Speedway who was a three-times South Island champion in speedway saloon racing.
Lomas Ainsley said his brother ''did everything; he had a go at everything you could think of''.
He was determined, driven and competitive, a high achiever, but also humble and discreet, never boastful.
Daryl Ainsley was a family man with ''a big heart'' who helped countless people practically, financially and emotionally.
''He would help out in any situation, he could handle anything. He helped a lot of people, not only in Central Otago but all around the country, and he was known internationally as well. But he would never tell a soul about anything he had done. He just got on with the job.''
Lomas Ainsley said his brother was passionate about the Central Motor Speedway, and determined to work for its future.
He had just secured funding for an irrigation system for the speedway, previously going there two to three times a day to move the sprinklers himself.
Police are investigating the incident on behalf of the coroner.
