Got it. I'm a bit of a fish myself so here's my most recent workout. Also happens to be one of my favorite workouts, it'll nearly kill ya if you let it.

Total: 2900

Warm Up
4 x 100 choice (about 1:30-1:35 pace)
4 x 150 swim, descend each interval from aerobic to tempo on :30 rest

Main Set
1 x 100 ALL OUT swim on :10 rest (1:10)
- 100 easy pull on :30 rest
2 x 50 ALL OUT swim on :10 rest (about 1:05 pace)
- 100 easy pull on :30 rest
4 x 25 ALL OUT on :10 rest (about 0:58 pace)
- 100 easy pull on :30 rest
2 x 50 ALL OUT swim on :10 rest (about 1:05 pace)
-100 easy pull on :30 rest
1 x 100 ALL OUT swim on :10 rest (1:12)

Cool Down
5 x 200 easy pull with paddles (I skip anything with paddles due to a shoulder injury, and swim this one) (I don't use paddles so I'm back to a slow easy 1:30+)

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