New neighbours issue.

In your position I would be telling the kids that people are allowed to show boobies in their own gardens and that they shouldn't be staring into people's gardens from their bedroom windows anyway, because it's rude.

Seriously, they were sitting in a hot tub, not having a wank. It's fine.

I'd not make a big deal out of it with DS and agree with others saying it's just boobs BUT I would stick a note through and let them know that they can be seen. They might not have realised and will want to put a screen up for their own privacy.

They're just breasts in a hot tub. It's not like the man is openly masturbating

Would you be so offended if someone was breastfeeding in public?

Why would someone who sits naked in their hot tub, surrounded by houses be embarrassed that neighbours can see her breasts?

I would put a note through the door make it jokey. Say your children have said they've seen "your boobies". I'm sure you're unaware that they could see. Just to save you further embarrassment :). Welcome to the neighborhood ;)

Trellis at bottom of garden

Plus film on the window

I have to say that nudity wouldn't bother me and I would explain to them some people choose to be nude

I'd pop round and let them know. Not for myself or my kids, nudity isn't a problem for me, but so they are aware that their private space isn't very private. They deserve to know that one of your windows overlooks their garden.

This.

I can't believe how prurient the OP is.

And your post has serious "won't somebody please think of the children" vibes. The world doesn't revolve around our children.

Tell him to shut the blinds if it bothers him.

They aren't being naked at you. How often does anyone spend staring out if that window.

You aren't powerless, you can absolutely avoid seeing them and IMO you'd be helping your kids to minimise it by saying that we all have bodies and they have every right to be naked in the hot tub and if we don't like it then we don't look.

Words like boobies and saying that it isn't a pretty sight is immature and unhealthy. It's just a body.

Op didn’t mention genitalia, she said that the ladies breasts were visible.

I think you may have to put a barrier up in your own garden rather than them doing it, as anyone who is happily naked in an overlooked garden is unlikely to take anyone else into consideration. I wouldn't be happy with it if it was a regular thing.

They are not strutting, they are sitting in a hot tub.
Of course they should be a bit more circumspect if overlooked but you make it sound like they are dancing around the garden naked.

I hate my neighbours so maybe I'll invest in a hot tub and get my wrinkly baps out!

I would let the neighbours know that they can be seen by small children but if they are ok with that, then leave them to it and just explain, as said above, that it's just bodies.

@ToddCat66
You're being ageist. And it's absolutely OK to say "boobies" (if you must) without the doubly coy 0s.

If the house backs on to you, do you mean the ends of your gardens meet? Can you put some high fencing at the end of your garden, or trellis on top of existing fencing to block the view?

It’s you who has an issue so you need to deal with it yourself. Put up a bamboo screen and tell your kids it’s rude to watch your neighbours through the fence.

Which is inherently suggesting something is wrong

Exactly.

So it would be OK if they were young and beautiful?

This. Unless the neighbours are purposely making a show of things, it’s no big deal.

'Oh well. It's just breasts. See them on the beach in summer all the time. They fed you too you know. No big deal. If you don't like it then don't look. Run along now.'

So the kids can't see out at all? That isn't the solution

Maybe use it as an opportunity to address your and your kids embarrassment of naked bodies. Instead of ‘doing something about it’ you could use the experience to educate your kids that there is nothing wrong with being naked and how people have rights and ultimately tell them if they don’t like what they see then don’t look directly at them
when they are in the hot tub.