Hope Unheralded

Continuing upstream, the recent snow event spurs you to make better time. For the next day, the travel is quick, though the resistance of the current is growing. The walls of the mountains are also closing in tightly until you find yourself straining to move forward through a narrow canyon. Fortunately, the water is fairly high at this time, and you're able to glide above the rocks. Still, the day is much shorter with the steep walls closing in, and there are few places to put in along this stretch of river. You are able to find a stretch of sand along the western shore, and put in for a rest.
Taking advantage of the break to look around, you realize there is a hidden cleft against the cliffside, which stretches back from the river and rises into the hillside. Anyone exploring up the cleft can make a Perception check (DC16) to notice a small cave opening several hundred feet further up the ravine.
Given the approach of night, there is sense in checking out the cave as a potential campsite for the night. It is about 50 feet up the hill from the edge of the river, so it should be safe from any change in water level. The cave is about 20 feet deep and 30 feet wide, with a possible opening in the darkness at the back of the cave. Looking around the outside of the cave entrance shows some signs that a path might have continued up the hillside through the cleft at one time, though it is now overgrown. Survival DC20 can notice the recent passage of a dwarf, that made an effort to cover his tracks.
There are no trees in the area for firewood, but there is a lot of scrub brush around that can be gathered and used for fire. There is not enough to create a roaring blaze, but the party can build a fire in the entrance of the small cave that will give enough heat to drive off the chill of the mountain air in the secluded cleft. Inspection of the back of the cave reveals a narrow passage that seems to weave back into the mountain for 8-10 feet then end. It is very narrow at the back, and appears to go nowhere.
During the night, 4 goblins drop down into the narrow passage from a hole in its roof at the back, and slip out to steal the party's unguarded equipment. Have anyone on watch roll Perception checks against the goblins' Stealth to determine whether they are successful. If the PCs suspect activity from the passage, give them advantage on their Perception roll. The goblins will try to each slip away with a pack, back into the passage.
If the goblins are discovered, one of them will bolt for the passage squealing loudly as the others turn to fight. This will bring six additional goblins on the next turn, with three of them coming down the hill to the cave entrance.
After a few rounds of fighting (have additional goblins enter the battle if the party is killing them too quickly), a terrible howl comes echoing down through the narrow canyon walls. A wild-haired, short figure in hide armor is barreling down the overgrown pathway up past the cave with a large axe held aloft. He will charge into the battle and swing wildly at every goblins within reach. The goblins will shrink back at the sound of his approach, and after he begins attacking must make a morale save to continue fighting. If the raging dwarf kills any of them, they roll the ST with disadvantage.
Once the goblins are driven off, the dwarven barbarian comes out of his rage and introduces himself as Karl Wyrmkill. He invites you to join him further up the hillside in his lodgings, and will offer to guide them overland through the hills past an upcoming waterfall three hours upriver. If they accept his assistance, he will also provide them with a +1 shield that he has found and has no use for.
Chances are, the party will have encounters with mountain creatures while passing overland - bears, mountain lions, etc. Karl will prove a useful companion in dealing with any difficulty for the next few days as they travel by land.