The Hauraki Gulf is at its most alluring - glassy calm and sparkling blue in the sunlight - and thousands of Aucklanders in small boats hover above the fishing reefs.
But even in such millpond conditions boaties are in need of help, sometimes in serious need.
On board the Coast Guard vessel Auckland Rescue Alpha, a crackling radio message announces that a small boat with two people on board has been seen waving a flag near the Rangitoto shipping channel.
Coast Guard volunteer master and crew chief Paul Fransham guides the powerful 9.5m Alpha over the wake of a fast-ferry towards the island as his four crew members try to pick out the troubled vessel on the horizon.
A man on a large yacht at anchor points to a small cabin boat near a channel-marking buoy.
It turns out two men and two children are on board. They are still pulling in fish as the rescue vessel arrives.
The skipper says the outboard motor would not start and now the battery is dead.
The volunteers take a battery on board and try starting the motor but it won't fire up.
Mr Fransham, a minister of religion who also has a commercial skipper's qualification, says it will be easier to tow the boat in to the ramp at Okahu Bay on Tamaki Drive from where the fishermen set out. He tells them to all put life jackets on and for the children to sit in the cabin.
The skipper says he has had the boat nine years.
"It's been a good boat. It's the first time it's let me down. "
The tow takes half an hour and the Coast Guard will charge about $140 for performing this service.
The rescue vessel receives another radio message soon after it leaves the bay.
It heads off at 30 knots towards the northern side of Rangitoto where a Coast Guard spotter plane is circling another stranded cabin boat.
The two men on this boat are smiling broadly. The motor refuses to start.
"It's never done this," says the skipper.
The tow line is used again, this time to take the fishermen across the channel to the Takapuna boat ramp.
Mr Fransham says dead batteries and poor quality fuel are common causes of boaties needing help.
The volunteers began their shift at 10am and expect to work until at least 9pm. They can have up to eight missions in a shift and often don't finish until midnight.
They anticipate a busy time later in the day as boaties try to start motors to head home.
"These are millpond conditions but things can change in an instant.
"I have known days like this when suddenly, it's been all go."
On calm days, boats can be swamped by the wash of large vessels. Sudden jerks from wakes can cause falls that have broken bones. People can get nasty gashes from propellers.
"We are a fire engine on the water and an ambulance, too."
A 5m vessel came to grief on Monday at the treacherous Manukau Harbour bar. It was swamped by a wave, throwing its five occupants into the water. Terangi "Toots" Woonton, 59, and Kairangi Samuela, 53, both died, while three others survived by treading water for two hours before being plucked to safety by a passing boat.
The two men will be farewelled at a joint funeral today in Mangere.
Coast Guard's national operations centre received 276,679 radio calls in the past year and provided safety and information services, such as bar crossing reports.
"Sadly, this holiday season we've seen a significant number of boating-related fatalities and several incidents that could have ended very differently if it weren't for the efforts of Coast Guard, other search and rescue partners and members of the public that have reacted to calls for help," says Coast Guard marketing manager Georgie Smith.
Coast Guard has 2326 professional volunteers nationwide, who responded to 2849 calls for help. It has 78 rescue vessels and nine air patrol units.