What is open water swimming?
Any swimming competition that takes place in rivers, lakes, oceans or water channels. The only proviso is that tides and currents are minor - the athletes have quite enough to do trying to race each other.
Is it an Olympic sport?
Yes - but only at the 10km distance for men and women, where it is described as marathon swimming. Rio 2016 Olympic Games gold medallists Sharon van Rouwendaal and Dutch countryman Ferry Weertman are expected to compete at Loch Lomond.
What are the other distances?
At the Glasgow 2018 European Championships, men and women will separately contest 5km, 10km, and 25km races then get together as a four for the mixed 5km team relay. All competitions are freestyle.
Is the temperature of the water a problem?
Only if it drops below 16 degrees Celsius. The warm summer in Scotland has meant that Loch Lomond’s average water temperature in the weeks leading up to the competition reached 19C and regularly hit 20C in the afternoons.
One issue for competitors will be what to wear. Rules state that between 16-18C wetsuits are compulsory and, above that, optional. Wetsuit wearers can be 50 seconds faster every 1.5km than those who do not use them.
What else will the swimmers be wearing?
Goggles, a maximum of two caps, nose clip, earplugs and possibly a layer of grease. It is up to the chief referee to ensure that use of substances such as grease are 'not excessive'.
Swimmers will also have a race number on their arms, back and hands, and the clerk of the course will check that each competitor is correctly identified. He or she will also make sure that the swimmers have trimmed fingernails and toenails and are not wearing any jewellery or watches.
The 10km and 25km races are tests of endurance. Is there a provision for the athletes to refuel?
At the start of a race the swimmers will make use of feeding poles, no longer than 5m, which look like giant fishing rods with power drinks dangling as bait and displaying a national flag to help identify them. Compostable cups have replaced plastic bottles as part of the global battle against pollution.
When a race reaches its critical stage, many swimmers will not risk using the feeding station in case of accidental clashes or mix-ups. Power gels may be tucked into suits for the final surge and it has been known for athletes to store sustenance in condoms for consumption mid-race.
With all those bodies in the water are there a lot of clashes?
They are difficult to avoid, especially at the turning buoy and at the end of the race when there is a rush to touch the finish 'wall' - a vertical static area 5m wide which captures each athlete's time from two transponders, one on each wrist.
Accidents happen, but what about deliberate 'bad behaviour'?
If the referees feel that anyone is making intentional contact with a rival then punishment will follow. For the first infringement, a yellow flag and a card bearing the swimmer's number is raised. If the offender does it again, the flag becomes a red one and he or she is disqualified.