Cowell is an oyster-farming and jade-mining town on Franklin Harbour, a large, shallow, almost enclosed bay on the eastern side of Eyre Peninsula. Its jetty is included because the regional brief names Cowell; there is no published dive guide for it, but the Marine Life Society notes that the coast from Cowell to Arno Bay has many shallow reefs, in 2-4 m, that offer easy snorkelling, with eagle rays and Port Jackson sharks on the seagrass beds. The harbour's seagrass meadows are extensive and productive, supporting King George whiting, garfish, tommy ruff, blue swimmer crabs and squid, and the jetty piles carry algae and encrusting growth with small crabs and fish.

Eagle rays glide over the grass and Port Jackson sharks rest on the bottom in the cooler months. Dolphins are often seen in the harbour. As a dive, the jetty is shallow and visibility is often limited, but it makes a pleasant snorkel for travellers breaking the drive between Whyalla and Port Lincoln.

The shallow reefs along the coast towards Arno Bay are worth exploring on calm days for snorkellers with their own transport. Oyster leases occupy parts of the harbour; stay clear of lease infrastructure. Data confidence is low.

Divers heading further south will find better jetty diving at Tumby Bay (leafy seadragons) and around Port Lincoln, while those heading north can return to Whyalla for the cuttlefish in winter.

Cowell is on the Lincoln Highway about 110 km (1 hour 15 minutes) south-west of Whyalla and about 500 km from Adelaide. The jetty is at the end of the main street on the Franklin Harbour foreshore; park at the jetty head. Enter via the steps at mid to high tide or wade in from the beach – the harbour is shallow and tidal.

Franklin Harbour is an enclosed bay with a narrow entrance, so it is sheltered from gulf swell, but its shallow water is stirred by any strong wind and it drains substantially on low tides; tidal flow runs through the harbour entrance. Dive or snorkel at high water on calm days. Summer water is warm; winter drops to about 12°C.

At high tide, snorkel or dive along the jetty over the seagrass, looking for eagle rays and Port Jackson sharks, then return.

No operator; occasional snorkellers and divers passing through between Whyalla and Port Lincoln.