We sea her a lot. Claire Holt shot to fame on the Aussie drama H2O: Just Add Water, aka our after-school must-watch about a trio of teen mermaids. From there, it was onto The Vampire Diaries and Pretty Little Liars, which means the 33-year-old has been on our TV screen since before we could legally join Instagram.

Now Claire has created a line with Andie Swim, which counts Demi Moore as an investor and Ashley Graham and Lena Dunham as fans. Here’s how she translated her mermaid skills into a design gig, what it’s like teaching 2 little kids about social media, and why you should bring milk to the beach.

So many celebrities have bathing suits. How is your perspective different?
So, I think you’re totally right in saying that. What I love about Andie is they’re really committed to making sure that women feel comfortable. And Melanie [Travis], the founder, said to me, “When I wear a swimsuit, it’s the most naked I’ll ever be in public.” There’s a lot of trust that goes along with that, a lot of responsibility! And let’s face it, picking out a swimsuit can be really daunting. So she challenged me to join her in making that experience a good one, and helping women to feel comfortable in their skin. How could I say no to that?

You’re a literal mermaid, though! How can your suits help women who aren’t TV stars?
Ha! I mean, listen, it’s true that because I grew up swimming and I’ve spent my life on the beach, I know how a swimsuit should fit, and how it should hold together! But also, I’ve had 2 babies in the last few years. My body has changed and stretched in so many different ways. I understand what it means to dress all different kinds of body shapes, because my body has changed so much… This company is led by women, so they get that. And I’ve lived it.

True or false: One-piece suits are sexier than bikinis?
Ohhhhh, they can be very, very sexy. Incredibly hot. A backless one-piece? That’s amazing. The key is to think about which parts of your body you really like showing off, and find a one-piece that has less coverage in those areas. So if you love your butt, you want a higher-cut leg. If you have a larger bust, you might try a triangle top because it gives you more support, but it still lets you show off your body. We even have a high-neck one called the Bondi that I’m really into.

You created a “mermaid cut” bikini that’s always sold out. Do you think it’s because we’re still obsessed with H20?
Actually, I was obsessed with this one pair of workout pants. They had that sort of “v” shape on the waistband, and I thought it was so cute because you still get to expose your belly button, but it’s a little higher around the waist. And when you’re pregnant or you’ve just had a baby, your uterus is still getting back to its normal shape, you know? And it felt really comforting to have a little “hug” around my waist even though I still wanted to wear a bikini. People talk a lot about maternity wear, but they don’t talk about post-maternity wear. I made this to help fill the gap, but it’s cool to see how many other women love it, even if they’re not figuring out how to, like, surf and breastfeed at the same time. [Laughing.] Now you see what I mean, by women and for women.

Please tell us your best mermaid hair and beauty tips.
First, you need buckets of conditioner. Any time we went to film, the hair teams would put piles and piles of conditioner onto our hair. It protected it in the water, but also when we filmed underwater, the conditioner is how you get that really silky, smooth look. It’s why your hair stays together instead of swirling all around your face. And then—okay, I don’t know if this is based in any scientific fact at all, but I’ll tell you. They told us that if you put drops of whole milk in your eyes before you go into the water, when you open your eyes underneath the water, it won’t be painful and you won’t get redness. So the makeup team would have these eye droppers full of whole milk. I mean, I guess it worked! I can still see underwater!

Okay, my last question is very strange. And I apologize. But what is it like being famous on Instagram?
Ohhhhh. You know, it’s so interesting, because I inherently don’t want to say that I’m not a confident person. Because I feel like as I’ve gotten older, I’ve become more and more confident in myself. But my default mode is “people pleaser.” That means it was weird for me at first to share anything that wasn’t “great” or “amazing.” But once I did, I found that whenever I’ve gone through something in my life, and I’ve been honest and open about it, there’s just this overwhelming sense of support, which is such a cool thing… For example, when I had my miscarriage, I remember posting about it. And I think 40k people commented. They told me that I wasn’t alone. When I was struggling with breastfeeding and postpartum periods, so many mothers reached out to me. And I think that’s the most magical thing about social media.

Kind of like being naked but in a swimsuit?
Exactly! That’s exactly what it is. You’re really vulnerable and sometimes it’s too much, but sometimes it’s so amazing. The downside, of course, is that social media is this crazy sort of vacuum. I think, at times, you don’t really realize the ripple effect of it. I’m terrified at the prospect of teaching my children to navigate it… but by the time they’re old enough to be on Instagram, it probably won’t exist. We’ll all be living on Venus or something instead.