Leggy Laura Csortan, 49, shows off her stunning figure aboard luxury boat with Simone Holtznagel and Justin Hemmes

Laura Csortan is looking fit and fabulous at 49.

The former Miss Universe Australia and model turned heads as she showed off her trim pins in a snake print g-string bikini and black triangle top during a boat outing with a group of high-profile friends - including Justin Hemmes and Simone Holtznagel - on Sunday.

Pairing the skimpy swimsuit with a white captain's hat and dark sunglasses, she carefully balanced on the boat's edge.

She was later seen emerging from the water, using a railing to keep her stable.

At one point, the television personality tied a small black sarong around her waist while chatting with a group of women who were sunbathing on the boat.

Laura was joined by fellow model Simone Holtznagel, who wasted no time stripping down into her swimsuit as she soaked up the sun.

The 33-year-old showed off her enviable figure in a plunging black one-piece swimsuit as she lounged aboard the luxury vessel.

Adding a touch of Riviera chic to her look, Simone styled the swimsuit with a straw cowboy hat and wore her long blonde hair loose and tousled from the sea breeze.

At one point, Simone was seen reclining comfortably on cushioned seating, chatting animatedly with those around her as drinks and snacks were passed around the deck.

In another moment, she stood up to stretch her legs, giving onlookers a full view of her toned physique as she gazed out over the sparkling water.

Simone's boyfriend, Josh Clapp, kept things casual for the outing, opting to go shirtless and wearing sunglasses as he relaxed beside Simone.

The pair appeared completely at ease in each other's company, sharing smiles and conversation throughout the afternoon.

Justin was also spotted on board, embracing the laid-back summer vibe as he mingled with guests during the sun-soaked cruise.

The group appeared to be in high spirits, with glasses seen scattered across the table and laughter flowing.

Simone's makeup look was kept natural and beach-ready, with minimal bronzer and a bare lip, perfectly suited to the relaxed day on the water.

The boat outing comes as Simone continues to enjoy a loved-up chapter with Josh, while balancing her busy modelling career and high-profile social life.

Simone previously dated celebrity personal trainer Jono, 34, and they welcomed their daughter before ending things late last year.

Jono has since moved on with Love Triangle star Emily Ryder, with the two debuting their relationship on social media.

The pair have reportedly been dating for several months and are taking things 'very slowly'.

Jono and Simone dated for almost two years after meeting through Sydney's social scene and share a one-year-old daughter, Gia. 

The trainer, who owns the Acero fitness brand, remains one of Australia's most in-demand celebrity trainers, having worked with the likes of Rebel Wilson, Rita Ora and Michael Clarke.