Coombe Reserve in Mosman Park is one of the main Swan River dive sites, with a group of small wrecks close to shore in the shallows and two more wrecks in deeper water off the bank. Divingwawrecks counts seven wrecked boats at the Coombe in 7–22 m, none of which have been positively identified.

The shallow wrecks lie in 9–12 m within easy reach of the grassy kit-up area. There are two timber hulls about 5–7 m long, heavily decayed, one deeper and one shallower, the latter surrounded by beams, barrels and a small dinghy. Lines running north and south lead to further small dinghy wrecks. They are small but make good navigation targets and habitat.

Marine life is sparse and mostly encrusting: anemones, sponges and sessile invertebrates on the timbers, with seahorses, gobbleguts, stripeys and sea stars. Large anemones are a feature. At night the river comes alive with prawns and crabs.

Visibility is usually poor, typically around 3 m, and dark water after rain is common. The river is a working and recreational waterway with boats, water skiers and kayakers, and the reserve has no dive flag, so bring your own.

The shallow wrecks suit Open Water divers comfortable with compass navigation and low visibility, particularly on days when the ocean is too rough. Divers with Advanced training can add the deep wrecks off the same reserve.

River temperatures swing more than the ocean: about 22–26 °C in late summer but as low as 13–15 °C in winter, when a 7 mm suit or drysuit makes a long dive more comfortable. Rinse gear well afterwards, as the estuary water is often high in organic matter.

Coombe Reserve is on The Coombe in Mosman Park, about 10 minutes from Fremantle; the suburban streets are confusing, so use a map or GPS. Parking is limited to about 10 cars, with a grassy kit-up area on the left. The shallow wrecks are reached directly from the kit-up area: one lies on a bearing of about 355° and the other about 145°, with smaller dinghy wrecks joined by lines running north and south.

Unaffected by ocean swell. Currents are stronger towards the centre of the river, so dive near slack water and on neap tides. Visibility averages about 3 m and is reduced by tannin-stained runoff after rain, by dredging and by summer algal blooms.

Water skiers and boats are busiest on warm weekends.

From the kit-up area follow a bearing of about 355° to the deeper timber wreck, then return and follow about 145° to the shallower wreck with its beams, barrels and dinghy. Use the north–south lines to find the smaller dinghies. Ascend close to the bank.

Dived independently and by clubs as a bad-weather option.