When planning a through trip under Ease Gill, such as Top Sink to Mistral, it is advisable to become familiar with the way through the Earby Series first, where time can be lost between Stake Pot and the pitch into the lower series. A trip to Cape Kennedy is a good opportunity to gain familiarity with the route, as well as being a worthwhile trip in its own right.
Coming from the Stop Pot direction, the entrance to the Earby Series is on the left hand side of the passage a few metres before the start of the descent to the Stake Pot col. Coming from Stake Pot, it is the first passage on the right after the climb up from the col.
It begins as a reasonably-sized arch-shaped passage which after surmounting some boulders, turns back to the right and becomes smaller. The passage then traverses some small drops which are associated with the Stake Pot Inlet series. Make sure you stay up. There is then a half metre step down into another passage, close to a T-Junction with a rift passage going off to the right. Keep straight on, and clamber over or under a wedged boulder to enter a thin stream passage. Follow this joint passage through a series of minor acrobatic exercises. After a hundred metres, the stream enters from the left. Carry straight on, and after a further few metres duck under the right hand wall into a crawl that enters an aven with an in-situ iron ladder. This is Cunuck Aven, and the start of the Earby Series proper, which is off to the right as you step off the ladder.
The first section of the Earby series follows a large, mainly sediment-filled, phreatic passage, with a succession of crawls linking larger chambers. Although the way through is not always immediately obvious, it is not possible to go far wrong. At one point, there is a decorated low chamber on the left, and the way is through there. Eventually, there is a descending, narrow rift by the right hand wall, with a continuation alongside it up over some boulders. Either way will do, but the latter is easier, and leads to a climb down into a larger chamber. The descent looks disconcerting at first, but traversing along the ledge leads to an easy, lightly-watered, scramble down a concealed crack.
The slope at the far side ascends into Brew Chamber, and from here a low crawl descends to the left. This leads into a flat-out downwards slither to the top of a slope over-looking Long Gallery, with the sound of a stream below. The easiest way on is to follow a thin rift between the wall and a boulder at the bottom of the slope to the half-left, which leads into a small chamber. Turning right here, follow a discrete passage which soon descends some boulders to a lower level. Continue traversing above the stream until a 3 m descent can be be made into an obvious pit - Rat Pit Chamber. The passage then passes under a gothic arch draped with stalagmitic curtains, to the start of a traverse. Another couple of metres reaches a rope which is the top of the descent into the lower series. From the main High Level Route to the top of the pitch takes about half an hour.
The passage to Cape Kennedy is to be found off to the right at the top of the pitch. This small passage soon enters a low chamber, with the main passage continuing, and a flat-out crawl leading off to the left. Follow the latter past a delectable crystal pool, into a larger continuation. Very soon you pass a tight descent on the right down which can be seen a pitch. A tight rift leads up into the base of Cape Kennedy Chamber, but this is more easily reached by ascending a larger slot a couple of metres further on, above a hole in the floor. A climb up an unstable boulder slope ascends into Cape Kennedy Chamber with its impressive array of stalagmites. The next chamber is Fire Hydrant Chamber, so called from the shape of the stalagmite in the centre. This prominent formation is surrounded by a pool of calcite, and within this can be seen a half-embedded bat skeleton. Beyond Fire Hydrant Chamber an active, well decorated stream passage leads to an aven.
The return is fairly straight forward, with only a couple of areas where it is possible to waste time. The exit from Long Gallery is not that obvious. Ascend the mud bank at the far end, and keep going when it seems to close down. The route through the phreatic chambers starts by following the right hand wall, but switches to the left hand wall after the decorated chamber. Ignore the next passage to the right which leads to a dig. Soon after this, the way on is a discreet passage to the half-right which returns to the iron ladder.
This is a worthwhile trip which traverses a wide variety of passages, and visits some of the more impressive formations in Ease Gill. It is, however, quite tiring and is probably not suitable for novices.