A tunnel big enough to drive a bus through is slowly being dug into a hill above Loch Ness for a £140m hydro power scheme. The BBC took a peek inside.
By Steven McKenzie
Highlands and Islands reporter, BBC Scotland news website
"It is like steering a ship," said engineering consultant Richard Appleby tramping along a gangway on the 220 metre-long Eliza Jane.
Except this "ship" is 100-metres underground.
Eliza Jane is a tunnel boring machine (TBM) gradually cutting a cavernous tunnel to carry water for the Glendoe hydro power station on a hillside above Fort Augustus on the shores of Loch Ness.
Mr Appleby's analogy came as he walked by the machine's control room with its bank of monitors, one showing the angle at which the TBM is digging.
From here operators control its roll, pitch and yaw - just like that of a ship.
So far the monster machine has munched its way 800 metres into the heather-covered hillside. It has got just under 8km (4.9 miles) still to go.
Broken up rock, or spoil, is transported along a conveyor belt to reduce the need for dumper trucks and the better quality stone can be used for building roads.
On this day the TBM was not operating.
The tunnel echoed with the voices of workers - many of them Polish - and the gurgle and slurp of pumps sucking at pools of muddy grey water.
The Eliza Jane, above, will be 300 metres underground when it bores to its deepest point
The workforce of 300 will rise to 500 at the peak of the work on the site
Power produced at Glendoe will be equivalent to a £100m 50-turbine wind farm
Overhead a huge duct draws in fresh air from outside.
Yellow lights hanging from the walls show the way from the outdoors to the Eliza Jane - a hulk of metal work, powerful hydraulic rams and thick black coils of electrical cables.
Local schoolchildren were invited to come up with a name for the TBM when it arrived at Glendoe after a long journey by sea and road from China.
They decided on Eliza Jane after first considering Tin Lizzie - a character in the Beano - and then changing their minds because it was not "posh enough".
Another quirk of the work being done for the Scottish and Southern Energy (SSE) scheme is that the tunnel has been blessed.
Superstitious workers will also place an icon of Saint Barbara - the patron saint of miners as well as artillery gunners and mathematicians - somewhere near or inside the tunnel sometime soon.
Workers' sensitivities are not the only thing SSE have been mindful of.
According to the company, it has been careful to protect areas of scientific and archaeological interest as well as habitats important to water voles, slavonian grebe and rare mosses at the site of the power station's 920 metre reservoir.
The reservoir is about an hour's drive from the tunnel site.
Once completed - in about two years time - the scheme will be capable of producing 100 megawatts - enough to power every household in Glasgow.
Until then the Eliza Jane is using more power needed for Fort Augustus - population 600 - to cut its way through a sea of rock.
SSE consider Glendoe to be the last large scale hydro power scheme that will ever be built in the UK.
Environmental constraints makes it harder to find suitable land for such developments to be created in the future.
When Glendoe is finished hydro's ship will finally have sailed.