The parish extends from Port Groudle in the south to the Snaefell mines and Brandywell Corner (on the TT course to the east of Beinn-y-Phott), a distance of some 6 miles (10 km), and contains an area of 15 square miles (39 km2). It is an upland district, being hilly and barren, and dropping sharply into the sea, with the exception of a few small deep, sheltered glens. The highest point in the parish is Mullagh Ouyr (near Snaefell) at 491 metres (1,611 ft). Its coastline is high and rocky, and broken by several headlands and small bays. The main headlands are Laxey Head, and Clay Head; and the bays are Bulgham Bay, Laxey Bay, Garwick, and Port Groudle. The only significant valleys are Laxey Glen, famous for its romantic beauty, extending from the Snaefell mines to the sea and Glen Roy, which leads into Laxey Glen at Laxey village.
The former parish church is at Boilley Veen. It was built in the 19th century as a more conveniently located substitute for the ancient structure of St Adamnan's Church. This 19th century church closed in October 2014 owing to lack of funds for maintenance, leaving Lonan with no parish church.