The welcome sight of orca in Tauranga harbour this summer is expected to continue as long as the harbour's underwater environment is looked after.

The orca come into the harbour looking for stingrays – an orca delicacy, says Mount Dive Club member Shane Wasik.

Tauranga harbour denizen watching the clean up.

'The orca come into the harbour chasing stingrays as a food source, with the stingrays in turn feeding on crustaceans, molluscs and fish that live near, in or around the bottom,” says Shane.

'If we continue to pollute and damage our waters, then all levels of the food chain can be affected. Remove the stingray food and you remove the stingrays, then the orca don't come back.

'It's a simple way of explaining food webs, but everything is related in the ocean.

'It is a fragile place and we should seek to take better care of it.

'The little things you do, such as dropping that bottle or washing your car near the storm water drains all make a difference.”

Shane is also organiser of the Mount Dive Club's recent clean up of the harbour floor at Pilot Bay.

They didn't go far from Salisbury Wharf because of bad weather, but still managed to find more than two tonnes of rubbish.

'Every dive surprises me with the amount of marine life in the harbour.

'On our cleanup dive alone, I spotted schools of mackerel, red moki, snapper – along with a number of octopus foraging around.

'Most of the rocks are covered in sponges and seaweed, where many small fish such as triplefins or seahorses hide.

'Octopuses hide in the many holes beneath rocks, lying in wait for their next meal, often just two eyes peering at you.

'You can also see yellow moray eels hiding under rocks but they are usually fairly frightened of divers.”

While the harbour may look murky on the surface, Shane says a diver's eye view reveals a kaleidoscope of colour and abundant marine life that we should seek to look after and protect.

'We take our harbour for granted,” says Shane.

'The heavy commercial and recreational users take for granted its ability to drain our waste and stormwater, and continue to use it to feed us with fish and shellfish.”