In the first incident, police were called to an alert at Taieri Mouth at 12.40pm, following report a vessel had flipped coming back across the bar at the mouth of the Taieri River.
Senior Sergeant Steve Aitken said four men - a male in his 40s and three males in their 20s - ended up in the water.
The men, who had been on a fishing trip, were able to float on top of the boat, which drifted close enough for them to make their way to shore, he said.
They were all wearing lifejackets and none was hurt in the incident.
Their boat was later pulled ashore north of Taieri Mouth by Brighton Surf Life Saving Club volunteers.
At 3pm, police and the lifesavers were called to south of Brighton after a boat's engine failed near Green Island at 3pm.
The three divers on board - a 26-year-old and two 25-year-olds - were uninjured and were rescued by the Brighton volunteers in an inflatable rescue boat.
The 4.5m vessel remains on the island, Snr Sgt Aitken said.
Police were then alerted at 6pm to the plight of a 43-year-old Dunedin man on a 5m cabin cruiser, which had lost power and was drifting south off the coast near Bull Creek, south of Taieri Mouth.
Snr Sgt Aitken said the man had first called a colleague on shore for help about 5pm, but the colleague was unable to locate him and called police.
Search and rescue staff were alerted, a helicopter dispatched and a commercial fishing boat, Lady Ann, asked to help. The man was found about 7.50pm after he set off aerial and smoke flares to help guide his rescuers, and was towed to Taieri Island by the commercial fishing boat, to be collected by Brighton surf club members. The man was cold but unhurt. However,
his pet black Labrador jumped overboard during the tow and was last seen swimming towards shore, Snr Sgt Aitken said.
He said it would have been preferable if the man's colleague had called police immediately.
''Notifying police [earlier] . . . allows more time for us to try and locate vessels in daylight. We were lucky to find the boat prior to it getting dark.''
Search and rescue co-ordinator Senior Sergeant Brian Benn said the incidents were a reminder to boaties to ensure they maintained their vessels and carried adequate communications equipment.
