An injured seal waddled up to a sleeping couple's Tauranga ranchslider for a noisy wake-up call - the latest in a string of bizarre encounters in the city.

The Department of Conservation says seal sightings have become the "new normal" in the Bay of Plenty, a possible new breeding ground for a species bouncing back in population.

Gerald and Joy McDonnell were in bed when they heard a loud thumping on their harbour-side home at 6.30am on Wednesday.

When Mrs McDonnell went to investigate, she first mistook the large wet animal sprawled across her patio for a dog.

A trail of blood from a wound near its flipper stretched from their patio to the shoreline nearby.

"I put the hose on it and then it just started drinking the water ... I think it must have been dehydrated," Mr McDonnell said.

"So I just grabbed a couple of rubbish bins and managed to push him back toward the water."

It was the first time the couple had been called upon by a seal, and Mr McDonnell hoped the smelly visitor would be the last.

"At least not at that hour of the morning. I don't want our house to be a seal colony," he said.

It is believed to be the same seal that earlier spent a day relaxing in a pedal boat at a nearby adventure park.

It came after another slippery tourist picked Mt Maunganui's Main Beach for a sunbathing spot, while a few weeks before, a worried onlooker who swam 16m to what appeared to be a stranded dolphin instead found he'd disturbed a hostile seal.

And in December, a fur seal pup that managed to climb through a catflap, up a flight of stairs and on to the couch of a Welcome Bay home made headlines around the world, the UK's Daily Mail matching a picture of the snuggled-up seal with a headline "Pipe and flippers, sir?".

DoC ranger Pete Huggins said the McDonnells' visitor had likely fled from the cold in the South Island, where populations had been rebounding.

By Jamie Morton @Jamienzherald Email Jamie