Xiis is reached from Erigavo, the regional capital of Sanaag, which is itself a long drive from Hargeisa. The road from Erigavo to Xiis descends through the Sanaag highlands to the coast — a spectacular route through mountain passes with views across the Gulf of Aden, but rough enough to demand a 4WD vehicle. Allow three to four hours for the journey from Erigavo, longer if the road has deteriorated. There is no public transport on this route. You will need a private vehicle, either hired in Erigavo or brought from further afield.
The road from Hargeisa to Erigavo takes around eight hours in good conditions. Erigavo is the logical place to fuel up and stock supplies before continuing to Xiis — there is nothing available at the coast. Bring enough water, food, and fuel for your entire stay, as there are no shops or services in Xiis capable of supplying a traveller. Travelling with a local contact or fixer from Erigavo is strongly advisable — they will know the road conditions, can help with directions to sites like Salweyn, and will smooth interactions in a town that sees almost no outside visitors.