To go swimming in the sea whilst the kids are in bed?

I actually think it’s fine.

Well yes. You chose to have 2 children. Of course you can't leave them alone in the house while you go off for a romantic dip. It'll be a long time before this is an option unless you get a babysitter

No you absolutely can't leave your preschoolers to go swimming. They need to be looked after, all the time!

I completely understand your hesitation—you're clearly thoughtful parents who are prioritizing safety and trying to weigh the risks. In practical terms, your plan sounds very cautious: Kids are asleep and not likely to wake. You're only 15 meters away, house in full view. Smoke alarm audible through open window. No appliances running = reduced fire risk. You've even got a backup babysitter plan. Honestly, it doesn't sound negligent at all. It’s probably safer than some parents being inside but distracted (e.g. with headphones on or in deep sleep). The comparison to having a private swimming pool in your garden is a fair one. Still, I think the slight discomfort you're feeling comes from the cultural norm that you should always be physically inside the house while your kids are asleep. It’s not necessarily about actual danger—just what feels acceptable or not. Personally, if you feel confident, you’ve covered the safety bases, and you’re staying close and vigilant—I’d say: YANBU.

Behave yourself

Quite, also, the OP's justifications are all over the place.

Fifteen metres through the garden from the door to the edge of the water.
Already far enough.

Would never be more than 30 metres away and in full view.
So 15 metres in the water....

Take around 30 seconds to get into the house from the furthest point we'd swim to.
So running at 1 metres per second including in the water.....

Beggars belief!

Absolutely crazy to suggest. You can’t just assume they will be okay because they have been every other night and regardless of the dangers you think in the water or that might not be there.. swimming can always be dangerous. Not only that but if one of your children wake up looking for you and not there anything could happen. They are pre school age and 100% need your presence.

You don’t have to miss it though you just have to be sensible, you have friends that would come around if you die in the sea or whatever and don’t return in 30mins so are clearly open to helping, so have them come around and watch tv and keep an eye on everything.

Not really sure why you’re bothering to ask on here, it sounds like you’ve already made your mind up about it.

Whereas you can see thorough walls when swimming in the sea?

Totally! Being sarky for being called out.

Imagine prioritising a romantic swim over your kids safety.

If it’s a romantic swim it means you won’t be concentrated on the house/ windows etc. You and your partner will be concentrated on each other so you can easily lose sense of time or not notice something.

So if you see a fire from the sea. You then swim to shore. Get out and run to the house.
I think thats sensible. House fires are known to be slow . You could maybe get to bedrooms and get kids out .
And thats just one of the many reasons you dont leave young children alone in a house .

Who?

The McGanns only left their child for a short time .My answer is Do not leave them alone.

Why can’t your friend that was going to come round if they hadn’t heard from you come round to watch them while you both swim?

15 seconds to swim ashore and reach your house?

So 15 seconds for a child to wander into the sea whilst you and whoever the other person/people in your 'we' are distracted, banging in the sea/lagoon/lake/paddling pool?

And you’d be watching the doors and windows whilst swimming out to see in the opposite direction?

😂😂

Oh, yuk. Everyone knows what you're doing and it's horrible.

Finally! A sensible suggestion.

Take it in turns, OP, or get your friend to come over for half an hour. I live by the sea in the UK — presume you're UK too. The sea is like a millpond today, totally calm and safe. But of course the people who live in Birmingham and Manchester think you'll be contending with crashing waves and rips.

Young children can be traumatised by what adults regard as minor things, like waking up on a hot night and finding themselves locked in and no adult around. I wouldn't and I'm more laissez-faire than most.

Can one of you go for a wank in the lagoon while the other watches the monitor? Then swap.

Hmm I mean we have often left our small children in bed while we've been at the bottom of the garden, and we have gone over to a neighbours house across the road (our house visible from their garden) - but we had a monitor on both of them that at the time, that I could access on my phone so I could watch them the whole time.
I probably wouldn't feel comfortable going in the sea. It's not like you can keep an eye on them and just nip back if there an issue, you can't know if they're ok, and something could also happen to you (though I appreciate you've tried to safeguard that with your friend after 30 mins).

"Should I leave my sleeping kids alone in the house while husband and I go for a shag in the sea?"

Come on!