[isostatic]

The question seems "can you swim 250m" or "500m"

Both of those are excessive "can you swim" questions. US scouts standard for "Swimmer" is

Jump feet first into water over the head, level off, and begin swimming.

Swim 75 yards in a strong manner using one or more of the following strokes: sidestroke, breaststroke, trudgen, or crawl; then swim 25 yards using an easy resting backstroke. The 100 yards must be completed without stops and must include at least one sharp turn.

Rest by floating…Long enough to demonstrate ability to rest when exhausted.

[avar]

Respectfully, those standards are crap. I'm from Iceland, and just looking up the swimming standards all 15 year olds have to pass and which I and everyone in the country had to pass as part of secondary school:

1) Swim 600 meters in under 20 minutes without stopping or touching the bottom.

2) Perform a rescue swim of 15 meters with a peer without stopping or touching the bottom.

3) Dive for 15 meters.

Those US scout standards are something Nordic countries might subject 6 or 7 year olds to.

The context of this thread is asking an able-bodied adult if they can swim before going to the beach. As in swimming in the ocean, an uncontrolled environment where there's waves and currents.

An able-bodied adult that actually knows how to swim should be able to swim for at least several kilometers in the open ocean without drowning or dying from exhaustion, assuming Mediterranean temperatures and waves that aren't higher than 1-2 meters.

[titanomachy]

By "dive for 15m" you mean "swim 15 horizontal metres while underwater", right? Diving 15m deep is a pretty elite skill.

[JackCh]

He almost certainly means 15 meters horizontally. Besides most hobby free divers not going to 15 meters very often, I'd wager 15+ meter deep pools are pretty uncommon even in Iceland.

[OscarCunningham]

Or perhaps "dive into the water from 15m above it"?

[titanomachy]

Also a relatively elite skill, though.

[DuskStar]

At least when I was a scout (~6 years ago now, Eagle) those were the standards you had to meet to swim in a pool/lake where you couldn't stand. But there was still significant monitoring of swimmers - lifeguards plus a buddy system where every 5-10 minutes you'd have a "buddy check" where you had to join hands with your buddy and hold them up out of the water while they counted the number of pairs.

The requirements for the Swimming Merit Badge aren't all that much better, though.

[JackCh]

>"The requirements for the Swimming Merit Badge aren't all that much better, though."

As I recall the "lifesaving" merit badge at least requires 400 yards without stopping, which is a lot more reasonable. If it were up to me that'd be the standard swimming test, but I suppose they want an accessible "skill ramp".