Wallis Lake is the large coastal lake and estuary system behind Forster and Tuncurry, and while it is not a scuba diving destination in any conventional sense, it does see occasional informal use — mainly for sheltered, current-free training dives when ocean conditions rule out the coastal sites, and for recreational scallop and shellfish diving where local regulations and seasons permit. The lake's water is characteristically murky, stained by tannins from surrounding wetland catchments and stirred by a soft silty bottom, so visibility is typically limited to just a few metres at best, making it a poor choice for anyone hoping for a scenic reef-style dive. What the lake does offer is complete shelter from ocean swell and current, a genuine advantage for basic skills practice, confined-water-style training in slightly more realistic conditions than a pool, or simply getting in the water on a day when the coast is unworkable.

Divers interested in scalloping or shellfish collecting should check current NSW DPI Fisheries rules on seasons, size and bag limits before taking anything, since these can change and enforcement is active in popular estuary systems like this one. Overall, Wallis Lake is included here for completeness given its prominence in the local landscape and its occasional recreational diving use, but it should not be mistaken for one of the region's scenic dive destinations — visiting divers are much better served by Forster Dive Centre's ocean and Seal Rocks trips for a genuine diving experience. Anyone tempted to treat it as a scenic dive destination in its own right will likely be disappointed compared with what the coast just outside the lake entrance offers.

Wallis Lake has numerous public access points and boat ramps around Forster, Tuncurry, Coomba Park and Green Point; a wade-in entry is possible from several foreshore reserves, or a small boat can reach deeper sections of the lake for scalloping or shell collecting dives. No commercial dive charter runs dedicated Wallis Lake trips; this is an independent/private activity.

Completely sheltered from ocean swell, making it diveable in virtually any weather, but visibility is characteristically poor — often just one to five metres — due to the lake's silty, estuarine bottom and tannin-stained water from surrounding wetlands. Best after a dry spell when less sediment is being washed in from the catchment.

Enter from a foreshore reserve or small boat and explore the shallow, silty lake bed slowly, using a compass or line for navigation given the very limited visibility; treat this primarily as a training or shellfish-collecting exercise rather than a scenic dive.

No commercial dive operator runs trips on Wallis Lake; dived informally, mainly for training in a sheltered, current-free environment or for recreational shellfish/scallop collecting where permitted.