FATMAP difficulty grade
From the Haberl Hut, cross the Serratus Glacier under the west face of Serratus.
Ice at the low buttress off Serratus may be quite difficult if not snow-covered.
At the Ionia-Serratus Col, drop down onto the flats of the Crescent Glacier and head for the lowest point of rock, the NE Buttress of Ionia.
This is one of the most excellent routes in the Tantalus! Start at the low toe on the glacier and scramble up 3rd/4th class ramps up and left until you can turn an exposed corner. An amazing quartz studded slab pitch leads back up to the crest with a 5.5 step up.
More scrambling/climbing leads up the crest until a headwall.
One 30m 5.5 pitch climbs decent rock up the left side of the headwall followed by a second 30m 4th class pitch. Continue up ledges into a groove that seems improbable until you step up right to a notch and an awesome exposed handrail jug traverse left onto easier ground.
Follow easy terrain along the crest to a sub-summit and down climb a notch.
At the notch, you face a left and right option to gain the next sub-summit.
The left option is easier and a bomber hand jam.
One 5.7ish move and you're on easy terrain.
The right option is slightly less strenuous but more exposed and looser rock.
Walk off the sub-summit and drop onto the west side of the divide along steep heather slopes until you're forced back onto the crest.
Here another AMAZING cracked slab takes you up through a groove at low-5th but very secure moves.
A few more steps over blocks and slabs and you're on the summit! Descend the S face on VERY loose 3rd class to get to a notch.
Depending on the status of the snow plug/serac, you may be able to make one rappel east here to get to the glacier.
If the snow is still there, climb a loose single pitch up to the next sub-peak and then continue over that, down climbing 4th class to the next notch where there's a slung block lets you rap east to the snow back onto the Crescent Glacier! 2x 30m ropes will be sufficient for the climbing pitches if you are willing to go unroped on the 3rd and easy 4th class portions.
A small alpine rack is helpful for the climbing pitches.
Most belays are possible on slung blocks.