A man and a 12-week-old puppy were helped to safety from the sea at Clevedon Pier in Somerset earlier.
Portishead RNLI lifeboat, the Coastguard helicopter from St Athan, Clevedon and Portishead Coastguard Rescue Teams were sent to rescue the pair.
The puppy was swept into the sea and the man then went in to rescue the dog.
The coastguard helped both of them to safety, issuing a warning never to enter the water to rescue another.
Witness Jolyon Rea said: "It was quite dramatic and the coastguard were absolutely fantastic.
"The dog was swept into the sea and ended up on the rocks near the yacht club."
He added that a man stripped off and went in after the puppy, called Bo.
Coastguard units then arrived, followed by the helicopter, and helped get the man and the puppy out of the water at about lunchtime.
Clevedon Coastguard Rescue Team said: "Today, 12-week-old Bo took a swimming lesson, unfortunately without a teacher after taking a fall into the water.
"Dogs are naturally very strong swimmers, even against the tides, and Bo managed to make his way to the safety of the rocks ready for collection. Albeit a little cold.
"We strongly advise never to enter the water in order to save another life because things can escalate very quickly.
"Phone 999, and ask for the coastguard if you see anyone in danger on or near the coastline.
"We can be there quickly, and it's easier if we only have one life to save."