My how times change! According to John Reseck Jr, writing in his 1975 book

SCUBA Safe and Simple, divers use knives underwater to:

1. Pry Things-"Like scallops"

2. Pound Things-"Like rock and coral"

3. Scrape Things-"Like old ship hulls"

4. Cut Things-"Like fish line"

5. Cut Things-Like "kelp"

6. Get Attention -"Signal to another diver by banging it against your tank"

7. General Use-"There is always something to poke at or pry up."

8. Wreck Diving-"A sharp knife is important ... wreck diving"

9. Cave Diving-"A sharp knife is important in cave .... diving"

10. Prepare Lobsters"Disjoint it (freshly boiled lobster )with the (dive) knife

1. Pried Things-"Like the won't move battery top on my Nikonsis V"

2. Pounded Things-"Like my won't move dive bag zipper."

3. Scraped Things-"Like the muck of my flippers (Love Ontario Diving)

4. Cut Things-"Like pizza-post dive caloric rush"

5. Carved Things-"Like pumpkins for the annual underwater contest (Love Ontario Diving).

6. Got Attention-"Signal to another diver by banking it against your tank (some things never change)"

7. General Use -"Left knife in dive bag just in case boat crew wanted to use it to fix the engine while we are underwater. They didn't.

8. Wreck diving-"A sharp knife removed zebra mussels so that divers could glimpse wreck (Love Ontario Diving)

9. Cave diving-"Buddy needed knife to convince me stick my head into a cave.

10. Prepared Lobster-hook on dive knife excellent at opening tinned meat (and lobster) after key lost.