A flat, fast course means that the first Brighton Marathon could see some exciting times.
Over 12,000 runners are expected to take part today, with many travelling from across the UK.
You can hear full coverage on BBC Sussex across the day - we will have reporters out across the city.
Many runners have great stories to tell and the layout of the course means spectators can get a good look as well.
The 26.2 mile course starts in Preston Park to the north of the city centre and then moves down the London and Lewes Roads before hugging the coast for most of the way.
That means it is mainly flat and organisers are hoping that this will mean an 'exciting and fast' race.
They have offered incentives to elite runners - those who can complete the course in less than two hours and twenty minutes.
People to watch out for
Many of those running have great personal stories
Former England and Leeds star Danny Mills will be taking part in a wheelchair.
He aims to raise money for the Association for Spina Bifida and Hydrocephalus and disabled football supporters. (ASBAH)
"One of the difficulties I have faced for the challenge is the danger of training on the road in a wheelchair and I have had to use the track to build up stamina and technique.' he said.
"Another problem is getting a decent grip on the wheels of the chair when it's wet - so I'm praying for a sunny day on 18 April."
Matthew Rhodes, a former soldier who was injured in a motorbike accident in Germany and cared for by
St Dunstan's in Ovingdean
St Dunstan's, is taking part.
You can find out
more about Matthew here
Rob Henderson, the former Ireland and British and Irish Lions centre, will be running to raise funds for
Wooden Spoon, a charity that helps underprivileged children achieve their full potential.
Tony Bloom,the chairman of Brighton and Hove FC, is aiming to breaking the four-hour barrier and raise £100,000 for
, a charity for sick children in Sussex.
Norman Cook, aka Fatboy Slim, is also running.
What do the coloured numbers on the vests mean?
The colours of numbers vests show the time in which the runner is expected to complete the course.
B&W are for elite, world class runners. Red: an expected time of between 2 hours 45 minutes to 3 hours 45 minutes. Blue: 3 hours 45 minutes to 4 hours. Pink: 4 hours to 4 hours 15 minutes. Green:4 hours 15 minutes to 4 hours 30 minutes. Yellow: 4 hours 30 minutes to 5 hours. Orange: 5 hours to 6 hours
Where to watch
The route passes through many of Brighton's major public areas so spectating should be easy.
The organisers have set up entertainment at points along the route. See
Mini miles for children are also being held on the day along the seafront.