You can join the Binevenagh Scenic Route at Downhill on the way from Coleraine or 1km after crossing the river Roe, coming from Limavady. From Coleraine you will pass Castlerock and then as you descend to sea level at Downhill you will see a sign for the Binevenagh Scenic Route which is on the left.
The drive follows the Bishops Road up to the top of the mountain which has some truly spectacular views over Magilligan to Donegal. One of my favourite drives, there is a stopping point and picnic site called Gortmore at the top. The road is not marked with central white lines, so you need to drive carefully. On the right day the gliders from Ballarena skim along the cliff tops and the views are just fabulous. Further along the drive you can find an access road leading to the lake on the top of Binevenagh. The route drops down onto Magilligan and takes you past St Aidan's Church and rejoins the Causeway Coastal Route near Bellarena Primary School.
Coming from Derry it is very badly signposted. If you follow the Causeway Coastal Route over the river Roe and towards Magilligan, look out for a sign for St Aidan's and the Holy Well which will be on the right hand side, the road is the Duncrun Road. Follow this until you see the Leighery Road and this will take you up to the Bishops Road, turn left and follow this over to Downhill. The highlight of the this drive is the views which are spectacular on a clear day, there is also St. Aidan's where the saint is buried and also the grave of Denis O'Hempsey, one of Ireland's greatest harpist. You can take some nice walks to the lake on Binevenagh or from St Aidan's. There are other roads which traverse the high ground these will lead back to the old inland road to Limavady and also to the Sconce which was an ancient citadel.