Signalling was initially done using flags, however by 1831, a three-armed semaphore (an upright post with arms) was operating which was capable of dealing with 666 code signals.
This was replaced in 1838 by a six-armed semaphore over 24 metres high which could handle over 900 000 separate signals.
Semaphore messages were sent by raising and lowering the arms to set positions. A 20 word message could be sent from Hobart and received at Port Arthur in 15 minutes. Three signal men usually worked and lived on site, often accompanied by their families. Work was carried out in all weather conditions on watches of three hours from 6am to 9pm. The current cafe and restaurant is in a building built for the head signalman in 1897.
Management of the Mt Nelson site was transferred from the Marine Board to the Parks and Wildlife Service in 1979.
Today, the station retains a strong link with the past. Every day, the Tasmanian State flag is flown, and International Marine Signal Flags are used to welcome visiting ships and for other special occasions. Fantastic photo opportunities of the beautiful views back across Hobart and down towards the entrance to the Derwent. The cafe and restaurant offer nice, reasonably priced meals whilst sitting on the balcony of the old Head Signalmans cottage taking in the views. A great way to pass away a quiet afternoon. There is a picnic area nearby with unsheltered picnic tables and BBQs and for those feeling a bit more energetic, the adjoining Bicentennial Park and Truganini Conservation Area both have extensive walking tracks.