Loch Maree, the largest sheet of fresh water north of Loch Ness lies between grid reference NG 874 786 and grid reference NH 015 645 in the district of Wester Ross, Scotland. The loch trends in a NW-SE direction along a major fault line, and at its southerly end is entered by another fault which runs from Loch Meallan an Fhudair down through Gleann Bianasdail and incidentally tapping Lochan Fada. The following details are extracted from the Bathymetrical Survey of the Fresh Water of Scotland; (Murray & Pullar, 1910):
"The length of the loch is 13½ miles (21.7Km), and the maximum breadth is rather over 2 miles (3.2km). The mean breadth is nine-tenths of a mile (1.4Km), being 7% of the length. Its waters cover an area of over 11 square miles(28.5Km2) and the islands nearly 1 square mile (2.6Km2). Loch Maree has a large shore development i.e. the length of the shore-line is much greater than the circumference of a circle whose area is equal to that of the loch. The shore development is 3.15, being greater than that of any other large loch in Scotland. The drainage area is 171 square miles, or 15 times the area of the loch. The greatest depth obtained was 367 feet (111.8m). The volume of water is estimated at over 38,500 millions of cubic feet (1090 million cubic metres), and the mean depth at 125 feet (38.1m). Loch Maree is divided into three main basins- (1) that extending from Isle Maree to the south-east end of the loch, which may be called the Ghruididh basin; (2) that lying to the south of the islands, which may be called the Slattadale basin; and (3) that extending from the north-east of Eilean Ruairid Mòr to the north-west end of the loch, which may be called the Ardlair basin."
The north side of the loch is particularly precipitous, with many parts where it is impossible to approach the loch edge, this side is dominated by the towering heights of Slioch (980m.) from which a range of smaller mountains extend down the loch to Ardlair. The south side of the loch is lined with mountains such as Meall a' Ghiubhais (878m.) but these are set back from the loch side, while the A832 road runs close to the loch for a considerable distance. Such is the nature of the shore line however, there are a number of places where it is not possible to get to the water's edge to take samples. The level of the loch can vary considerably as is shown by the debris "tide marks", and a variation of one metre would be a conservative estimate. That the loch can be exceedingly rough is shown by the various "storm beaches" with large stones and shingle piled up on them.
Two trips were made to Loch Maree, both based in Kinlochewe. The first trip took place between 20/4/97/ and 25/4/97. This was in the form of a reconnaissance. Thirteen samples were taken from Loch Maree while five samples were taken from neighbouring lochans. The second trip took place between 7/6/97 and 13/6/97 and this was joined for four days by Professor D. Mann and Dr. S. Droop. Forty-nine samples were collected during this trip. On the final day of sampling, as no boat was available, an eighteen mile round trek in torrential rain (and midges) was required to sample further in parts of the north shore. Sixty-two samples were therefore collected from sites around the loch. Every sample is given an "E.Number", which is recorded in a log book kept in the Royal Botanic Garden, Edinburgh. The record of samples is given over the page.