Dark Hole is about a detective and a wrecker driver who have to fight for their lives against mutants that are created when humans breathe mysterious dark smoke from a sinkhole.
OCN revealed the casting news of Kim Ok-vin and Lee Joon-hyuk on October 9, 2020.[10] On December 11, 2020, Yoon Jung-hoon was confirmed to join the cast[11] and on December 14, 2020, Jang Sung-won reportedly joined the cast.[12] The photos from the first script reading were released by OCN on March 2, 2021.[13]
In the table above, the blue numbers represent the lowest ratings and the red numbers represent the highest ratings.
This drama airs on a cable channel/pay TV which normally has a relatively smaller audience compared to free-to-air TV/public broadcasters (KBS, SBS, MBC and EBS).
NR denotes that the series did not rank in the top 10 daily programs on that date.
^Park Chang-ki (March 19, 2021). "'다크홀' 김옥빈X이준혁, 4월 24일 첫 방송 확정" ['Dark Hall' Kim Ok-bin x Lee Jun-hyuk, confirmed for the first broadcast on April 24]. Ten Asia (in Korean). Retrieved March 22, 2021.
^Lee, Se-Hyun (2021-03-03). "이하은 '다크홀' 출연" [Lee Haeun to appear in 'Dark Hole']. sports.khan.co.kr (in Korean). Archived from the original on 2021-04-22. Retrieved 2021-03-11.
^Son, Jinah. "'타임즈'부터 '다크홀' '보이스4'까지…OCN, 2021년 라인업 공개" [From 'Times' to 'Dark Hole' and 'Voice 4'... OCN unveils lineup in 2021]. MK스포츠 (in Korean). Archived from the original on 2021-04-22. Retrieved 2021-03-11.
^Kim, Seong-hyun (2020-10-09). "김옥빈·이준혁, OCN '다크홀' 캐스팅 확정… 변종인간 액션 스릴러" [Okbin Kim and Junhyuk Lee confirmed to cast OCN 'Dark Hole'... Variant Human Action Thriller]. YTN Star (in Korean). Archived from the original on 2021-04-22. Retrieved 2021-03-11.
^Kim, Myung-shin (2020-12-11). "윤정훈, '다크홀' 출연 확정…대세 행보" [Yoon Jung-hoon confirmed to appear in 'Dark Hole']. TV Report (in Korean). Archived from the original on 2021-04-22. Retrieved 2021-03-11.
^Cho, Yeong-gyeong (2021-03-11). "장성원, 레드우즈 전속계약…OCN ´다크홀´로 복귀[공식]" [Jang Sung-won, Redwoods exclusive contract... Return to OCN 'Dark Hole' [Official]]. isplus.live.joins.com (in Korean). Archived from the original on 2021-04-22. Retrieved 2021-03-11.