Best way to prepare for your swim tests is to spend time in the pool swimming laps. I was in the same boat many years ago - for my original open water course we had to swim 40 lengths of a 25 metre pool. I got into the pool and trained hard, and just managed to make the 40 lengths. After completing and passing the swim tests, I never went back to the pool. That was a mistake
When I took the Divemaster program, I was again challenged with swim tests. Back to the pool and train hard. Completed the swim tests and the Divemaster program. This time, however, I continued to swim. A regular swimming routine not only improved my health, but helped make my dive times longer with less air consumption. I worked my way up to the point that I was regularly doing two mile swims, and when I felt good, an occasional three mile swim.
Unfortunately many years of swimming led to other issues, including rotator cuff problems in both shoulders. I have had to give up swimming and miss the time in the pool, but the time I did spend swimming lengths was time well spent.
Divegoose
When I took the Divemaster program, I was again challenged with swim tests. Back to the pool and train hard. Completed the swim tests and the Divemaster program. This time, however, I continued to swim. A regular swimming routine not only improved my health, but helped make my dive times longer with less air consumption. I worked my way up to the point that I was regularly doing two mile swims, and when I felt good, an occasional three mile swim.
Unfortunately many years of swimming led to other issues, including rotator cuff problems in both shoulders. I have had to give up swimming and miss the time in the pool, but the time I did spend swimming lengths was time well spent.
Divegoose