On Sunday, 28,000 runners from all over the world will participate in the 45th annual Honolulu Marathon.
The city says it's taking measures to ensure its a safe race.
Following recent terror attacks at large-scale events, like the Boston Marathon and the Las Vegas massacre, marathon organizers say enhanced security measures are necessary.
"All this has changed in the last few years, so we're grateful for the support to keep this marathon strong, successful, and, of course, most importantly safe," said Jim Barahal, president of the Honolulu Marathon.
The mayor echoed his comments.
"There have been horrific events around the world recently -- just tragic events -- and we never want to see that occur here in the City and County of Honolulu or the State of Hawaii," said Honolulu Mayor Kirk Caldwell.
Security officials say there are no credible or direct threats to the marathon at this time.
But no one is taking any chances.
The city says one of the key safety features this year is that teams, along with 27 cameras, will be monitoring the entire 26.2-mile course before, during, and after the race.
Honolulu police will have 400 officers on duty at the race and paramedics will have crews ready to assist runners.
Also, authorities will monitor social media for any suspicious posts and those who own drones are being asked to keep them on the ground.
"It creates a very dangerous activity over the crowds where we will have upwards of 25,000 people beneath the drone. We will, where possible, monitor and identify any illegal drone activity and seek enforcement of any existing FAA laws," said Rick Taniguchi, Honolulu Marathon organizer.
And a heads up for drivers: Road closures will begin at 12:30 a.m. Sunday with tow-away zones in effect until 5 p.m.
"We will be citing and towing cars if they are parked along the route. The signs vary on times depending on the areas, so please heed the signs," said Tai Fukumitsu, of the city Department of Transporation Services.
The Honolulu Marathon, which is the fourth largest in the nation, begins near Ala Moana Beach Park at 5 a.m.
Here's a full list of the roads that will be closed or restricted Sunday:
18th Avenue from Diamond Head Road to Kilauea Avenue until runners clear the area. Traffic will be detoured at Diamond Head Road and Makapuu Avenue. Local traffic only access to Diamond Head Crater by Civil Defense, FAA, and National Guard personnel.
Ala Moana Boulevard from Atkinson Drive to Ward Avenue will be detoured from 12:30 a.m. to 4:30 a.m. in preparation for the 5 a.m. marathon start.
Ala Moana Boulevard/Nimitz Highway from Ward Avenue to Nu‘uanu Avenue from 2:30 a.m. Koko Head-bound traffic will be detoured left to Smith Street. Use Vineyard Boulevard as a detour route.
Diamond Head Road, Kahala and Kealaolu avenues will be controlled by police when the volume of runners would interfere with the safe movement of vehicles and runners.
Hawaii Kai Drive makai lanes from Kalanianaole Highway to Keahole Street from about 2:30 .m. until the area is clear. The mauka-side lanes will be contra-flowed for two-way traffic.
The H-1 Freeway in both directions from the Waialae Avenue off-ramp/22nd Avenue to Ainakoa Avenue. H-1 traffic will be detoured from 3:30 a.m. until 2 p.m.
Kahala Towers, Kahala Hotel and Resort, and Waialae Country Club traffic will be permitted via Aukai Avenue and Pueo Street when safe.
Kalakaua Avenue will be detoured left onto Kuhio Avenue from 3:30 a.m.
Kalakaua Avenue mauka-side between Monsarrat Avenue and Poni Moi Road from 4:30 a.m. until the marathon is over. The makai lanes will be contra-flowed for two-way traffic at about 9 a.m. Limited to resident traffic only; patrons of the Outrigger Canoe Club and Elks Club must enter via Kapahulu Avenue.
Kalanianaole Highway from Ainakoa Street to Hawai‘i Kai Drive makai-side will have restricted access from 2:30 a.m. The mauka-side of the highway will be contra-flowed for two-way traffic. West-bound Kalaniana‘ole Highway traffic will be detoured onto Ainakoa Street to Malia Street to Kilauea Avenue.
Kalanianaole Highway will be closed to through traffic from Hawai‘i Kai Drive to Keahole Street from about 3:30 a.m. until the area is clear. Traffic will be detoured onto Hawai‘i Kai Drive via Kawaihae to Lunalilo Home Road. Maunalua Bay boat ramp traffic must enter from the Koko Head end.
Kapahulu Avenue makai-bound will be closed at Kuhio Avenue at 1:30 a.m. Local traffic will be allowed after 9 a.m.
Kapiolani Boulevard in both direction from King Street to Piikoi Street at 2:30 a.m. Ewa-bound traffic will be detoured to Pi‘ikoi Street.
Keahole Street makai-bound lanes from about 2:30 a.m. until the area is clear.
Kealaolu Avenue from Wai‘alae Avenue to Kahala Avenue from about 5:30 a.m. until the area is clear.
Kilauea Avenue from 18th Avenue to Waialae Avenue; all east-bound lanes will be closed at 4 a.m. until runners clear the area.
King Street from Nuunau Avenue to Kapi‘olani Boulevard from 2:30 a.m. Traffic will be detoured at Smith Street.
Monsarrat Avenue from Kalakaua Avenue to Paki Avenue from 4:30 a.m. until event is over (limited to tour buses).
Paki Avenue from Monsarrat Avenue to Kalakaua Avenue from 4:30 a.m. for the duration of the marathon.
Piikoi Street in both directions from Kapi‘olani Boulevard to Ala Moana Boulevard from 2:30 a.m.