DEN - ISP

$108 Find Cheap Flights from Denver to Islip

This is the cheapest one-way flight price found by a KAYAK user in the last 72 hours by searching for a flight from Denver to Islip departing on 10/25. Fares are subject to change and may not be available on all flights or dates of travel. Click the price to replicate the search for this deal.
1 adult
1 adult, Economy

KAYAK searches hundreds of travel sites at once for deals on flights to Islip

 
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Denver to Islip, as well as popular online travel agencies
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Denver to Islip, as well as popular online travel agencies
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Cheap Flights from Denver to Islip (DEN-ISP)

 
Here are some of the best deals found on KAYAK recently from the most popular airlines for round-trip flights from Denver to Islip that are departing in the next months. While these flights were available on KAYAK in the last 72 hours, prices and availability are subject to change and deals may expire.
Discover the best prices for you by selecting your travel dates on KAYAK.

Recent round-trip flight deals from Denver to Islip

Sat, Sep 6 - Sat, Sep 13
Frontier Logo
11:59 pm - 9:04 amDEN-ISP
7h 05m1 stop
Frontier Logo
5:05 pm - 11:13 pmISP-DEN
8h 08m1 stop
$236Frontier
Find Deal
Fri, Oct 3 - Wed, Oct 8
Frontier Logo
12:04 am - 10:55 amDEN-ISP
8h 51m1 stop
Frontier Logo
5:05 pm - 11:16 pmISP-DEN
8h 11m1 stop
$238Frontier
Find Deal
Fri, Sep 12 - Tue, Sep 16
Frontier Logo
12:04 am - 10:55 amDEN-ISP
8h 51m1 stop
Frontier Logo
11:25 am - 10:14 amISP-DEN
24h 49m1 stop
$239Frontier
Find Deal
Thu, Oct 2 - Wed, Oct 8
Frontier Logo
12:04 am - 10:40 amDEN-ISP
8h 36m1 stop
Frontier Logo
5:05 pm - 11:16 pmISP-DEN
8h 11m1 stop
$258Frontier
Find Deal
Fri, Aug 29 - Mon, Sep 8
Frontier Logo
12:19 am - 6:38 pmDEN-ISP
16h 19m1 stop
Frontier Logo
5:05 pm - 11:13 pmISP-DEN
8h 08m1 stop
$259Frontier
Find Deal
Thu, Sep 18 - Mon, Sep 22
Frontier Logo
11:59 pm - 9:04 amDEN-ISP
7h 05m1 stop
Frontier Logo
5:05 pm - 11:13 pmISP-DEN
8h 08m1 stop
$265Frontier
Find Deal
Thu, Sep 11 - Mon, Sep 15
Frontier Logo
11:59 pm - 9:04 amDEN-ISP
7h 05m1 stop
Frontier Logo
5:05 pm - 11:13 pmISP-DEN
8h 08m1 stop
$275Frontier
Find Deal
Thu, Oct 2 - Sun, Oct 5
Frontier Logo
12:04 am - 10:40 amDEN-ISP
8h 36m1 stop
Frontier Logo
9:49 am - 8:04 pmISP-DEN
12h 15m1 stop
$278Frontier
Find Deal
Sun, Oct 19 - Thu, Oct 23
 Logo
7:44 pm - 1:45 pmDEN-ISP
16h 01m2 stops
 Logo
11:40 am - 11:15 amISP-DEN
25h 35m3 stops
Mon, Sep 29 - Sat, Oct 4
 Logo
11:59 pm - 1:24 pmDEN-ISP
11h 25m1 stop
 Logo
11:53 am - 11:57 pmISP-DEN
14h 04m2 stops
Booking Insights

KAYAK's insights & trends for Denver to Islip flights

Get data-powered insights and trends into flights from Denver to Islip to help you find the cheapest flights, the best time to fly and much more.

What’s the cheapest day of the week to fly from Denver to Islip?

The average price of all round-trip flights from Denver to Islip clicked on KAYAK for each day over the last 12 months.

If you are looking for a flight deal from Denver to Islip, look for departures on Thursdays and avoid leaving on a Wednesday, as it's usually the priciest day. When flying back from Islip, Wednesday is the cheapest day to fly and Friday is the most expensive.

Good to know

Low seasonNovember
Cheapest flight$108
Best time to beat the crowds with an average 20% drop in price.
Most popular time to fly and prices are also 13% lower on average.
Flight from Denver to Islip

When to book flights from Denver to Islip

Are your dates flexible? Find out the best times to travel from Denver to Islip based on our flight data from the last year. Discover the cheapest month and even day to fly.
Estimated round-trip price
KAYAK looks at all historical flight data for each date to provide a predicted price for one-way trips or round-trips with a duration up to 40 days. While we try to provide actual minimum prices for each date, some prices are predictions and actual prices may differ.

FAQs for booking flights from Denver to Islip

  • What is the cheapest flight from Denver to Islip?

    In the last 3 days, the lowest price for a flight from Denver to Islip was $108 for a one-way ticket and $236 for a round-trip.

  • Do I need a passport to fly between Denver and Islip?

    Even though you are not required to have a passport, keep in mind that an official ID is needed to board the airplane.

  • Which airports will I be using when flying from Denver to Islip?

    When flying out of Denver you will be using Denver Intl. You will be landing at Islip, also known as Islip Long Island.

  • Which aircraft models fly most regularly from Denver to Islip?

    We unfortunately don’t have that data for this specific route.

  • Which is the best airline for flights from Denver to Islip, Southwest or Frontier?

    The two airlines most popular with KAYAK users for flights from Denver to Islip are Southwest and Frontier. With an average price for the route of $456 and an overall rating of 8.0, Southwest is the most popular choice. Frontier is also a great choice for the route, with an average price of $248 and an overall rating of 5.9.

  • How does KAYAK find such low prices on flights from Denver to Islip?

    KAYAK is a travel search engine. That means we look across the web to find the best prices we can find for our users. With over 2 billion flight queries processed yearly, we are able to display a variety of prices and options on flights from Denver to Islip.

  • How does KAYAK's flight Price Forecast tool help me choose the right time to buy my flight ticket from Denver to Islip?

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight to Islip from Denver is likely to change within 7 days, so travelers know whether to wait or book now.

  • What is the Hacker Fare option on flights from Denver to Islip?

    Hacker Fares allow you to combine one-way tickets in order to save you money over a traditional round-trip ticket. You could then fly to Islip with an airline and back to Denver with another airline. Booking your flights between Denver and ISP can sometimes prove cheaper using this method.

  • What is KAYAK's "flexible dates" feature and why should I care when looking for a flight from Denver to Islip?

    Sometimes travel dates aren't set in stone. If your preferred travel dates have some wiggle room, flexible dates will show you all the options when flying to Islip from Denver up to 3 days before/after your preferred dates. You can then pick the flights that suit you best.

Reviews of the top airlines flying from Denver to Islip

 
See real verified KAYAK customer reviews for airlines flying from Denver to Islip. Airline scores are aggregated from all reviews left by passengers on KAYAK after flying with an airline. KAYAK doesn’t show reviews that are older than 5 years. Learn how KAYAK collects reviews.
Need help choosing which airline to fly with from Denver to Islip? KAYAK airline reviews give an overall score for each airline based on loads of factors, including comfort, boarding, in-flight entertainment and more, to make your decision easier. See airline scores according to verified KAYAK customer reviews.
8.0
SouthwestOverall score based on 4241 reviews
8.0Comfort
8.6Crew
7.0Food
8.1Boarding
7.5Entertainment
Airline reviews

southwest just starting charging for luggage. hadnt realized it until it was too late. now out $70 when i couldve bought a carry on if i wouldve known. free bags was one of the only reasons i chose southwest over another airline (the other being no assigned seats, which is apparently also being changed). stupid business decision. wont be flying southwest anymore.

2.0 MediocreAnonymous, Jul 2025AUS - RDU
Read more Southwest reviews

southwest just starting charging for luggage. hadnt realized it until it was too late. now out $70 when i couldve bought a carry on if i wouldve known. free bags was one of the only reasons i chose southwest over another airline (the other being no assigned seats, which is apparently also being changed). stupid business decision. wont be flying southwest anymore.

The quality of Southwest Airlines continues to degrade each time I fly with them. If it were not for the free luggage, I would probably choose another airline. Their prices are a little bit competitive, but way too high for the quality of the service. Southwest is not unique in this way. Domestic flight in the United States of America has continued to be a lower and lower quality product. Very sad when you compare the quality of domestic airlines to that of many international airlines around the world.

Very smooth checking in our luggage with a super pleasant SW agent. I enjoyed a fun entertaining movie.

WiFi did not work. For as outrageous as these flights cost, when they’re advertised with certain services/ features they should be in working order

Worst experience I had on Southwest. Still better than most, but the seating was barely tolerable.

The Southwest employees (all two of them) were very nice and cheerful despite the fact the line to self-check a bag (simply drop it off) was hundreds of people long. Thank God I arrived early to the airport because I stood in this line for at least an hour. Once on the flight that had been delayed by an hour, we had no Wi-Fi and thus no entertainment. Finally, I hope the investor strong arm tactics against Southwest pay off in a short-term windfall to your C-Suite because the rest of you are screwed. I have been a faithful Southwest customer for 15 years due to everything you just got rid of. I'm flying to Idaho and Washington in October, both places I used to simply book with Southwest without a second thought now with Frontier (Washington) and United (Idaho) because they offer everything the "new" Southwest does but cheaper and at better times, destinations, etc. This really makes me sad...

It was okay. The plane was delayed from earlier in the day, but they kept updating the departure time, sometimes later, sometimes earlier. That was stressful. Once we finally got on and took off, it was fine. I was supposed to have a connection in Chicago to Los Angeles, and the time for so late I was rebooked to arrive in LA 3 hours late. The departure time to Chicago later became early enough to have taken my original connection and arrive earlier but that wasn't an option.

It was one and half hour late... Not sure if any other experience matters.

Delayed flight. Nicest crew member was a SW pilot flying seated next to me who kindly move to seat the final passenger. Flight extra delayed. My cup of refreshment of ginger ale was so packed with ice it was literally 2 sips.

For my birthday trip this was my second time ever flying, this trip was the best.

I’m not gonna fly Frontier Airlines because booking is not an option. No water or food is for high price, not equipped for health emergency incompetent crew for emergency services. Cheap airline shows it is cheaper in all service categories. Boarding is the best of all airlines!

Very bad! No good service delayed my second connection flight

Frontier is terrible. Paid for exit row, not given exit row, refused to refund fee.

2 hour delay due to late plane, wrong size plane causing overbooking, and people getting off and on the plane after boarding was completed.

The worst. We never made our connection and they did absolutely nothing to help us at the airport.

I never got to experience the flight because they delayed my first flight and I missed this one. Then Frontier didn't want to help me rebook a flight to get me to my final destination.

The Boarding process in Denver was chaotic, and since the line was so long, we were lined up very far from the gate. If there were any announcements from the gate staff, we didn't hear them. The flight attendants were spectacular. The only negative part of the flight was sitting by a 2 1/2 year old who was unruly and unfortunately had parents that matched his behaviors. Also, the restaurants in Denver on the E concourse, they didn't have food (passengers could only order 1 item on the entire menu) or the restaurants had 12-14 people waiting for orders to be prepared and another 6 people waiting to order. If you have a layover in Denver and need to grab food, be prepared to visit the shops with pre-packaged sandwiches, or you can visit another concourse but it may take a while to transit throughout the airport.

Everything went as planned. Crew was great. Seats were still not that comfortable.

they delayed my flight which ended up, causing my layover flight to leave without me, resulting in me missing a flight and having to stay overnight in Houston international. I got no compensation other than a flight to my original location only a day later. i’ve never experienced such a unprofessional situation

The seats were extremely hard and uncomfortable, even for a budget airline.

Everything you need to know for your flight from Denver to Islip

Information on your arrival and departure airports

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