THE epic Ironman challenge returns to Bolton for the ninth time this weekend.

Thousands of endurance athletes are set to descend on the town to take part in the gruelling triathlon event.

They will be challenged to swim 2.4 miles in the choppy waters of Leigh’s Pennington Flash, cycle 112 miles around the hills of Rivington, Belmont and beyond, before running the entire length of a marathon towards a glorious finish in Bolton’s town centre.

IRONMAN 2017: The best places for fans to watch the action — from Pennington Flash to Bolton town centre

IRONMAN 2017: The names to watch in annual triathlon race across Bolton

To celebrate an incredible sporting weekend that also includes the Ironkids race, here are some facts you might not know about the Ironman race:

1. There are 2,345 athletes taking part in this year's race, 46 per cent of whom are competing for the first time.

2. The youngest participant is Boltonian Jordan Stanworth, who turns 18 on race day, and the oldest is aged 70.

3. Athletes have to complete the event in 17 hours and there are cut-off times for each discipline.

4. 20,040 gels, 25,000 litres of water, 2,414 litres of cola and 65 boxes of bananas will be consumed on course

5. 154 of this year's competitors are from Bolton.

6. 85 per cent of the participants are male and 88 per cent are from Great Britain.

7. Pro athletes are expected to cross the finish line from 2.20pm on Sunday.

8. There are three feed stations on the bike course which athletes will pass seven times. All will offer energy bars, bananas, water and Isotonic.

9. There are four stations on the run which athletes will pass ten times. All will offer gels, water, Isotonic and Cola. The Lane and Bark Street stations will also offer bananas, savoury biscuits and Red Bull.