The park protects two cave systems: the Artlish River Cave and a second passage called The Black Hole, with 396 meters of surveyed passage between them. What makes these caves exceptional is not their size but their context. This is Vancouver Island's last remaining undisturbed karst unit that includes a major river cave. Karst landscapes form when slightly acidic water dissolves soluble bedrock over thousands of years, creating sinkholes, underground drainage, and cave networks. Above ground, the forest that feeds this process stands intact. Old-growth western hemlock and red cedar rise from soil that has never been cleared, their root systems interlocking with the same limestone the river is slowly dissolving beneath them.

The A'licath people, part of the Kyuquot confederacy, gave the river its name. European records caught up in 1932, when a report to the Canadian Geological Survey first documented the caves. Local hunters, miners, and timber cruisers had known about the entrances for years, but formal exploration did not begin until the 1970s. Between 1974 and 1978, cavers surveyed both systems, mapping passage lengths and recording formations. The work produced something more valuable than measurements: it generated enough publicity to raise alarm about logging activity in the watershed. Timber harvesting had already reached the edges of the karst, and the caves sat exposed to the chain reactions that follow clear-cutting: increased runoff, sediment loading, collapse of fragile limestone overburden.

The BC Forest Service established a reserve around the two caves in 1977, a modest protection that acknowledged the caves' value without fully securing it. Nearly two decades later, in 1996, the reserve was elevated to full provincial park status. The timing mattered. By then, much of Vancouver Island's karst terrain had been logged or fragmented. The Artlish system survived as an intact unit partly because of its remoteness and partly because a handful of cavers and biologists pushed hard enough at the right moment. Today, the park shelters more than geology. Roosevelt elk use the surrounding forest as winter habitat and a migration corridor. The Artlish River supports sockeye, coho, chinook, and pink salmon, along with steelhead and rainbow trout. The old-growth canopy includes amabilis fir and Sitka spruce alongside the cedar and hemlock.

Reaching the caves requires commitment. The park lies roughly 80 kilometers south of Port McNeill and 78 kilometers northwest of Woss, along the Zeballos road. A secondary logging road once reached closer to the boundary, but it was deactivated in 2009, returning the approach to foot traffic. From the road end, a 4.5-kilometer hike brings visitors to the park boundary. Beyond that, more walking through old-growth forest is required before the cave entrances appear. There are no maintained trails in the conventional sense, no interpretive signs, no visitor center. The difficulty of access functions as its own form of protection, filtering out casual visitors and preserving the silence that has settled over these passages since long before anyone mapped them.