Timestamps:

Level 1: The Grave 00:00 - 27:00
Secret1 - 02:06
Secret2 - 03:25
Secret3 - 03:44
Secret4 - 04:00
Secret5 - 06:52
Secret6 - 07:53
Secret7 - 08:52
Secret8 - 12:50
Secret9 - 16:00
Secret10 - 20:30
Secret11 - 21:53

Level 2: The Shipyard 27:00 - 52:51
Secret1 - 28:50
Secret2 - 32:44
Secret3 - 33:06
Secret4 - 38:41
Secret5 - 41:30
Secret6 - 48:07
Secret7 - 51:15

Level 3: The Mine Town 52:51 - 01:10:08
Secret1 - 57:27
Secret2 - 58:24
Secret3 - 01:00:37
Secret4 - 01:02:30
Secret5 - 01:03:53
Secret6 - 01:05:16
Secret7 - 01:08:26

Level 4: The Mines 01:10:08 - 01:29:26
Secret1 - 01:16:42
Secret2 - 01:17:30
Secret3 - 01:19:10
Secret4 - 01:25:10

Level 5: The Crypts 01:29:26 - 01:49:19
Secret1 - 01:30:10
Secret2 - 01:32:39
Secret3 - 01:35:03
Secret4 - 01:38:02
Secret5 - 01:40:40
Secret6 - 01:43:00

Level 6: The Chapel 01:49:19 - 01:56:17
No secrets here.

Level 7: The Asylum Grounds 01:56:17 - 02:17:00
Secret1 - 01:59:55
Secret2 - 02:01:47
Secret3 - 02:06:35
Secret4 - 02:08:06
Secret5 - 02:08:53
Secret6 - 02:16:12

Level 8: The Asylum 02:17:00 - 02:32:47
Secret1 - 02:17:25
Secret2 - 02:17:50
Secret3 - 02:25:04
Secret4 - 02:27:28
Secret5 - 02:29:45

Level 9: The Excavation Site 02:32:47 - 02:55:00
Secret1 - 02:33:02
Secret2 - 02:36:58
Secret3 - 02:45:30
Secret4 - 02:52:58

Level 10: The Ritual Chamber 02:55:00 - 02:58:22
No secrets here.

Secret1 02:26
Secret2 06:44
Secret3 09:14
Secret4 11:23
Secret5 13:38