1) The room was extremely dark, with no light filtering in at all.

2) The forest became extremely dark as the sun set behind the mountains.

3) Her mood was extremely dark after receiving the bad news.

4) The alleyway was extremely dark and gave off an eerie vibe.

5) The storm clouds made the sky extremely dark in the middle of the day.

6) The movie had an extremely dark and suspenseful atmosphere.

7) The cave was extremely dark, with only the flashlight providing a small beam of light.

8) The night was extremely dark, and we struggled to find our way back to the campsite.

9) His thoughts turned extremely dark as he dwelled on past mistakes.

10) The painting depicted an extremely dark scene, filled with shadows and mystery.

11) Sure, here are some example sentences using the phrase "extremely dark:"

12) The cave was extremely dark with only a faint glimmer of light at the entrance.

13) The room became extremely dark as the storm outside blocked out all sunlight.

14) She found herself in an extremely dark alleyway with no one else in sight.

15) The forest grew extremely dark as night fell, making it difficult to see the path ahead.

16) The basement was extremely dark, and she fumbled for the light switch to find her way.