Duathlon, Stockton and Winchester

The swimming stage puts many would-be triathletes off – which is where the duathlon comes in. A standard duathlon is a 10km run followed by a 40km cycle and a final 5km run, but two new events, in Stockton-on-Tees and Winchester, are more accessible for beginners. Both feature novice (2/10/1km) and sprint (5/20/2.5km) distances, while Stockton also has a full-length race.
• Stockton: from £18, 21 April, trihard.co.uk. Winchester: from £25, 17 March, trytri.co.uk

Quadrathlon, Poland

On the other hand, some people find a triathlon not tough enough. Cue the quadrathlon, which adds a kayaking leg of anything between 4km and 20km to the standard swimming, cycling, running format. Britishquadrathlon.org.uk has a list of upcoming events in the UK and abroad, such as the new summer quadrathlon in Wolsztyn, in the west of the country, comprising a 1.5km swim, 40km road cycle, 8km kayak and 10km run.
• Around £42, 17 August, polskaman.pl

Adventure races, across England

The one- and two-day Questars races involve trail running, mountain biking and kayaking. Participants can choose how much of each stage to complete and in what order, and whether to do it solo or in a team. The Wyre Forest in Worcestershire and the Thames Valley in Oxfordshire are new for 2013.
• From £36 for one day or £79 for two (including camping), 27/28 April and 7 September, questars.co.uk

Big Green Bike Ride, London to the New Forest

This year, Friends of the Earth's annual charity bike ride is from London to the New Forest. Day one is an 85-mile cycle along quiet lanes in Surrey and Hampshire, while the optional second day involves a 40-mile exploration of the national park. Weekend riders will stay in a woodland campsite with locally sourced food and a bar, and can upgrade from tents to luxury shepherds' huts for an extra £15.
• £35 for one day or £75 for two, 27 and 28 April, foe.co.uk

Scafell Pike trail marathon, Lake District

This race through Borrowdale and up Scafell Pike is for experienced runners – the trails are tough; navigation skills are needed for unmarked sections; and anyone failing to run the first 17km quickly enough will not be allowed up the mountain. The pay-off is spectacular Lake District scenery and the accolade of completing England's newest and highest marathon.
• £35, 19 May, highterrainevents.co.uk

The Wall ultra-run, Hadrian's Wall

For those to whom a marathon over a mountain is but a walk in the park, a new 69-mile ultra-run in Cumbria and Northumberland follows the route of Hadrian's Wall. Run from Carlisle to the Millennium Bridge in Gateshead in one day, or walk the route in two (there is free camping, hot showers and a real ale bar at the halfway point).
• £135, 22 and 23 June, thewallrun.com

Big Chill swim, Lake District

New to the Lake District is a winter open-water swim in Lake Windermere. There is a choice of distances, from a 30m dip (suitable for novices) to a 450m endurance race (regular cold-water swimmers only). Beware: no wetsuits allowed …
• From £12, 2 February, chillswim.com

Trans Pyrenees cycle ride, France

Discover Adventure has a new challenge for 2013: a nine-day coast-to-coast ride from the Atlantic to the Mediterranean across the Pyrenees. The route includes punishing passes tackled by riders in the Tour de France, including the terrifying Col du Tourmalet (2,115m).
• £826pp with hotels and most meals but not flights, departs on 15 June and 7 September, discoveradventure.com