Questions & Answers about Når vi ror over fjorden, må alle ha på seg flytevest.
Both når and da can translate to when, but they are used differently:
når is used
da is used
- for a single event in the past:
- Da vi rodde over fjorden, hadde alle på seg flytevest. = When we rowed across the fjord (that time), everyone wore a life jacket.
- for a single event in the past:
In your sentence, this is a general rule or instruction (valid every time), so når is correct.