Each item refers to the answer to a puzzle. From the puzzle you can see what depth the puzzle is that. You then use the puzzle depth and dive/surface times with the PADI dive table to get the letters.
A speech (97 min) | RANT | Eh? | 40 ft | U |
A good day (27 min) | FUNDAY MONDAY | Imba | N | |
Plants (14 min) | ROSES | Hashi It Out | 60 ft | T |
Something you’ve heard before (170 min) | REPRISE | Time Is Out of Joint | A | |
Something you save for the end (21 min) | EIGHTBALL | A Puzzle Consisting... | 80 ft | N |
A squid (40 min) | BLOOPER | This Puzzle Has No Errata | G | |
An instrument (4 min) | TUBA | Hash | 110 ft | L |
Something by the door (48 min) | FLOORMAT | Escape from the Classroom | E | |
A computer program (30 min) | OPERA | Denizens of the Deep | 35 ft | L |
A sport interval (16 min) | OVER | Nope! | I | |
A fish with no scales (20 min) | STURGEON | Feeling Bluefin | 40 ft | N |
A colorful bird (55 min) | BLUEFINCH | Misspelled Insects | E | |
A point of entry (39 min) | CITYGATES | Per-verse Poetry | 50 ft | S |
Using PADI dive tables like the following (from http://www.scubatoronto.com):
a time and depth gives a decompression group letter. Then a “surface interval” time (given by the workshop puzzles which are on the surface) gives a new letter group. These are plugged into table 2:
Combined with the depth for the next dive, it gives residual minutes of nitrogen. Added to the minutes of the next dive, and plugged into table 1, this again gives a letter. For example, 97 minutes at 40 feet gives U. A surface interval of 27 minutes lowers it to N. On table 2, N at 60 feet (the depth of the second dive gives 35 remaining minutes. Added to the 14 minutes of the dive, gives 49 minutes at 60 feet, which in table 1, gives a T.
Follow this procedure to the end, alternating dives and surfaces, to get the answer, UNTANGLE LINES.