Still Wakes the Deep

In total, there are 10 dead crew members required to interact with in order to unlock this achievement.
Some are very easy to spot, some even are part of the gameplay, but others are a bit tricky to find.
This video should help you.

There are total 19 Crew member bodies in the game that are counted towards this achievement, many of them are counted automatically while you progress near them.
For some you have to press the button to interact to make it count.

The achievement unlocks at the very end of the game with automatic dialogue and cutscene, if you have interacted with every other bodies throughout the game.

03:17:35 - Drill Ops
03:23:05 - 18/19 Crew Member Body (Unmissable, Finlay's)
03:25:10 - "Body Count" Achievement

All the Crew members are timestamped below with all timestamps.

Extended Timestamps:
00:00:00 - Intro & Settings
00:01:45 - Accommodation
00:03:15 - Light switch (Electrical Appliance)
00:03:25 - 03 Cabins (missable)
00:05:00 - "McLeery" Achievement
00:05:35 - 02 Cabins (missable)
00:06:20 - TV in Crew Lounge (Electrical Appliance)
00:07:05 - 04 Conversations with crew members (Canteen)
00:09:15 - "All Beans and Forgiveness" Achievement

00:11:35 - Deck & Under Rig
00:12:05 - 04 Conversations with crew members (Deck)
00:15:10 - "Social Butterfly" Achievement
00:21:45 - "The Sickening of the Calm" Achievement
00:22:00 - 01/05 Sea Dive Death / 01 Death (Falling into Sea)
00:22:30 - Heater (Electrical Appliance)
00:27:55 - 02 Death (Falling from Balance Beam)
00:28:45 - 03 Death(Fire)

00:31:35 - LEG C
00:32:35 - 04 Death (Fall to Death)
00:36:55 - 05 Death (Steam)
00:41:45 - 01/19 Crew Member Body
00:43:05 - "Breathe In, Breathe Out, Repeat" Achievement

00:43:10 - Accommodation (Second Visit)
00:43:20 - Heater (Electric Appliance)
00:44:00 - 01 Phone-Call
00:48:30 - 01/07 Electrical Hazard Death / 06 Death (Electricity)
00:49:20 - 07 Death (Monster Veins/Blob)
00:51:30 - "Sailing By" Achievement

00:53:25 - Lifeboat Access (Port Side)
00:53:40 - 02/05 Sea Dive Death
00:56:00 - "Home by Christmas" Achievement
00:56:55 - 02 Phone-Call
00:58:25 - "Fahrenheit 0451" Achievement
00:59:00 - 03 Phone-Call

00:59:55 - Utility
01:02:15 - "Leaning Into It" Achievement
01:02:25 - "General Strike" Achievement
01:02:40 - 08 Death (Death by Monster - Trots)
01:05:20 - "Eye of the Needle" Achievement

01:06:00 - Deck (Second Visit)
01:07:05 - "Jetsam" Achievement
01:08:00 - 02/07 Electrical Hazard Death
01:10:00 - 02/19 Crew Member Body
01:11:47 - 03/19 Crew Member Body
01:12:35 - 04/19 Crew Member Body (not interactable)
01:12:45 - 09 Death (Death by Monster - Muir)
01:14:25 - 05/19 Crew Member Body
01:18:20 - 03/07 Electrical Hazard Death
01:21:40 - "Everything Breaks" Achievement
01:21:50 - 03/05 Sea Dive Death
01:22:45 - 04 Phone-Call
01:24:05 - 05 Phone-Call

01:25:00 - Administration
01:25:15 - 06 Phone-Call
01:27:15 - 04/07 Electrical Hazard Death
01:28:25 - 10 Death (Death by Monster - Rennick)
01:29:45 - 05/07 Electrical Hazard Death
01:30:55 - "I Am The King" Achievement

01:31:00 - Starboard Side
01:31:15 - 04/05 Sea Dive Death
01:32:55 - 07 Phone-Call
01:34:40 - 06/07 Electrical Hazard Death
01:35:35 - 11 Death (Gas)

01:37:25 - Engineering (First Visit)
01:46:40 - "Look At All This Mess!" Achievement
01:49:10 - 12 Death (Death by Monster - Addair)
01:53:10 - "Compression Ignition" Achievement
01:58:55 - "Into the Belly of the Beast" Achievement
01:58:10 - 08 Phone-Call

02:01:15 - LEG A & LEG B
02:02:05 - 13 Death (Fall while crossing pipeline)
02:03:50 - 06/19 Crew Member Body
02:08:55 - "Greased Scotsman" Achievement
02:09:10 - 07/19 Crew Member Body (he is in your way, no need to interact. Caz will make a remark after getting out of water)
02:09:30 - "Cerebral Anoxia" Achievement
02:12:25 - 08/19 Crew Member Body
02:13:40 - 09/19 Crew Member Body
02:19:10 - 10/19 Crew Member Body
02:19:40 - 14 Death (Death by Monster - O'Connor)
02:19:55 - "Finlay Destination" Achievement
02:23:20 - "Surfacing" Achievement

02:23:40 - Processing Quad (Accommodation)
02:24:00 - Heater (Electrical Appliance)
02:24:20 - 09 Phone-Call
02:26:20 - 10 Phone-Call
02:36:05 - "Beacon in the Dark" Achievement
02:36:30 - 05/05 Sea Dive Death
02:36:35 - "Full Fathom Five" Achievement

02:41:25 - Engineering (Second Visit)
02:47:10 - 07/07 Electrical Hazard Death
02:47:20 - "Not so Good with the 'Leccy" Achievement

02:51:25 - Accommodation (Third Visit)
02:51:30 - "Treading Water" Achievement
02:51:40 - Heater (Electrical Appliance)
02:52:05 - 11 Phone-Call
02:54:10 - 11/19 Crew Member Body (Automatic, unmissable)
02:54:30 - 12/19 Crew Member Body (Automatic, unmissable)
02:55:25 - 13/19 Crew Member Body
02:55:55 - 14/19 Crew Member Body (two bodies, count as one)
02:56:40 - 15/19 Crew Member Body (Automatic, unmissable)
02:57:20 - 16/19 Crew Member Body
02:57:40 - "Snoop" Achievement
02:57:50 - "Me and My Spoon" Achievement

02:58:45 - Roof and Marine Control
02:58:50 - "Beaufort Eleven" Achievement
03:01:00 - 12 Phone-Call
03:06:00 - 17/19 Crew Member Body
03:09:25 - "Good with the 'Leccy" Achievement
03:10:00 - "Leviathan" Achievement
03:14:05 - 13 Phone-Call
03:14:20 - "Clear Down" Achievement
03:16:30 - "The Drowning of Davey Rennick" Achievement
03:16:35 - 18/19 Crew Member Body (Unmissable, Probably Rennick's)

03:17:35 - Drill Ops
03:23:05 - 18/19 Crew Member Body (Unmissable, Finlay's)
03:25:10 - "Body Count" Achievement

03:25:35 - Derrick
03:25:40 - "The Horror Sings" Achievement

03:27:15 - Epilogue

After Credits:
03:31:30 - "Still Wakes The Deep" Achievement
03:31:40 - "Walking Simulator" Achievement
03:31:50 - "Bheir an cuan a chuid fhèin a-mach" Achievement

03:31:55 - Subscribe!