A record 950 rowers, forming 891 crews, will be competing at the championships this weekend.
''Entries have come from all four South Island rowing associations,'' Otago Rowing manager Karl Morgan said.
''Only a very small number of South Island clubs and schools are not represented.''
There will be 950 races in the 43 events over the two days.
It will be a massive day today with 10hr 30min of rowing, starting at 7.30am with the first of the two heats in the women's coxed four. The last race will be the men's open eight at 5.55pm.
Officials have given themselves a herculean task to get the heats through on time.
''We will have a race every four minutes instead of the usual five minutes,'' Morgan said. ''Finals will start at 7am on Sunday morning.''
The Olympic success has generated the increase in novice rowers this season.
''There are 13 entries for the novice eight,'' Morgan said.
''We used to just have a final.''
Most rowing schools in the South Island have entered crews. The exceptions are St Margaret's and St Bede's, of Christchurch, which have had their own rowing camp in the Marlborough region this week.
''The Wairau club and the Central RPC have opted to compete in a regatta at Lake Karapiro,'' Morgan said. There are 40 entries for the girls under-16 and under-17 single sculls and 12 in the under-18 singles.
There will be a celebration dinner in Twizel tonight to celebrate the five medals - three gold and two bronze - won at the London Olympic Games.
None of the Olympians or members of the elite rowing squad will be competing at Lake Ruataniwha. They will be competing at Lake Karapiro.
The Otago championships used to be held after the Christmas break but were brought forward two years ago because of the decision of Rowing New Zealand to hold the national championships in the third week of February.
A feature race will be the women's open single sculls that will test the ability of Zoe McBride (Otago).
She won three sculling gold medals at the national championships at Lake Karapiro and another three at the Maadi Cup regatta at Lake Ruataniwha last season.
She will face a strong challenge from Southern RPC rowers Lisa Owen, Kristen Froude, Olivia Loe, Tessa Young and Johannah Kearney. Nicola Shanks could be a dark horse.