Triathlons arguably rank among the toughest challenges for fitness fans, but for those who want something they can really brag about, there's the Artemis Great Kindrochit Quadrathlon.

The quadrathlon - which is held on 10 July and raises money for international aid charity Mercy Corps - is hailed as the hardest charity event.

The Scottish Highlands provide a spectacular location for the challenge, which starts with a 1.5km (0.8 mile) swim around Loch Tay and a 24km (15-mile) run/walk up seven mountains encompassing the Lawers and Ptarmigan ridges which reach up to 1,214m (3,982ft).

Next, back to Loch Tay for a 11km (seven-mile) kayak and 54km (34-mile) cycle. The clock doesn't stop until finalists slice a watermelon in half with a sword.

For those who don't want to do go it alone, there's a team option for up to eight people.