I always try to get to the pool first thing in the morning. It usually ensures at least a half hour of peaceful swimming before the little creatures show up

I swim in a hotel pool on a regular basis (I have a membership there) and the vast majority of the times adults actively police the kids 'keep out of the lady's way' etc. Occasionally I have to say something to the adult like 'hi, shall I stay on this side to swim my laps then' to non confrontationally let them know their activity is / could affect my swim. If the kids are older / no adult in the pool I will ask them nicely if they could keep to one side and most totally get it.

The Hyatt Newport Beach had what I thought was a decent solution: there was a lane marker on one side of their largest pool (appeared to be a 25 meter lane), and then no markers in other parts of the pool. That made it clear that a portion of the pool was intended for lap swimming, and we saw a couple people each morning using it for that.

If the hotel doesn't have the space for this, then a better idea is probably to find a local gym with a pool designed for lap swimming.

I love swimming and have kids who are on swim teams, but I'd never expect people to get out of our way in a smaller, recreational pool such as those found at 99% of the hotels in this world.

I remember seeing this same "confrontation" unfold in a pool that was maybe 15 meters long, with 20 swimmers in it, at the Renaissance in Vienna. Two old ladies, barely "swimming" at all, were angry and barking at everyone in the pool who wasn't staying in their own lane. No markers for lanes, no expectation at all that this was a lap pool, mostly adults just chilling out, plus a few kids messing around like kids do. (But definitely not playing Marco Polo.) I gave the ladies an earful and they gave it back...in German.

Shame on those non-adults for being in a non-adult pool...

I should correct myself, I meant kids in the general pool area. There were also kids in their own kids pool area.

Where I've seen a kiddie pool at a hotel, it's usually for toddlers. Bigger kids are in the "main" pool. It usually takes a pretty big resort for there to be an "adult" pool (sometimes with swim-up bar, which is awesome).

I've stayed in a few hotels that have an hour early in the morning and/or one late at night when no kids are allowed in the main pool.

At a hotel, I kind of expect the kids to be everywhere, but I'd also add that Marco Polo is a dumb game and they shouldn't play it in a crowded pool to begin with.

I've stayed in several hotels that claim to have an adults-only swim time, but I've never seen it enforced. Despite obvious signs at the pool, some parents seem to believe it doesn't apply to their precious little darlings

Finally! A real reason for doing laps.

someone needs to come up with a rule book with distances and drinks consumed for an aquatic equivalent to running's 'beer mile' contests