Ong Seong Wu recently went on an amusement park outing with former Wanna One groupmate Ha Sung Woon.

On February 24, the idol took to his personal Instagram to share some images from their day out, captioning the set: "Eternal youth."

In the first image, the two friends can be seen standing side-by-side as they take in the view of Everland, a popular amusement park based in Yongin, South Korea. The obvious height difference had many of Ong Seong Wu's Instagram followers thinking he was on a date, but later images revealed it was none other than Ha Sung Woon.

Ha Sung Woon also shared two selfies the boys took together on the trip to his own Instagram, playfully captioning the image with a cutesy way of saying 'Sung, Seong,' the two boys' names together.

Meanwhile, Ong Seong Wu is currently shooting upcoming JTBC drama '18 Moments.' Ha Sung Woon will also be making his solo debut this week.

Check out their Instagram post below!