Madeline Holtznagel shows off her growing baby bump in a black playsuit after touching down in a seaplane near billionaire boyfriend Justin Hemmes' Vaucluse mansion

Madeline Holtznagel was the picture of impending motherhood on Wednesday as she took in some sun in Sydney.

The mum-to-be, 27, is expecting her first child with billionaire boyfriend Justin Hemmes, 52.

The model was not afraid to flaunt her burgeoning baby bump after touching down in a seaplane, near Justin's Vaucluse mansion.

Madeline was ready for some fun in the water, wearing a form-fitting black playsuit.

The dark, one-piece garment finished at Madeline's taut thighs and showed off her growing baby belly.

Madeline also wore a pair of almond shaped sunglasses with a tortoise shell-like frame.

Tying her flaxen locks back for her coastal flight, Madeline accessorised with a gold heart-shaped pendant around her neck.

She also carried a light brown Akubra hat with a darker coloured leather band and a second, darker hat, possibly Justin's. 

Madeline was seen gingerly stepping out of the seaplane into the crystal clear water, being careful with her precious cargo.

A shirtless Justin was keen to make a splash, strolling through the water as he carried  a child, possibly one of his daughters - Alexa, nine, and Saachi, eight - on his back.

Madeline appeared to be having a great day out, beaming as she disembarked from the seaplane.

The couple were joined by a female pal who was seen happily chatting to Madeline as they stood in ankle deep water one the shoreline.

it appears the group was preparing a fruit-filled feast with the pal also carrying a large tray of fresh peaches. 

A source confirmed the exciting news of Madeline's pregnancy to Daily Mail Australia in November and revealed a friend of Justin's recently moved out of his Vaucluse mansion to make room for their growing family. 

Justin, who has a net worth of $1.39billion, already has daughters Alexa and Saachi with his ex-girlfriend Kate Fowler, from whom he separated in 2018.

The business mogul then began dating Madeline the following year, when the model was 22 and he was 47.

They have been spotted out together in recent weeks looking as loved-up as ever,  recently attending Pilates queen Bernadette Fahey's wedding to Jordan Sukkar.

Justin and Madeline quietly began seeing each other in 2019, a year after his debut on the Financial Review Rich List with an estimated net worth of $951million - which has since risen to $1.39billion.

Though they generally keep their romance under wraps, the couple are often seen disembarking from his sea plane after enjoying luxurious family holidays with his two daughters.

The couple have gone from strength-to-strength since going public and even sparked engagement rumours in June 2023.

Eagle-eyed fans noticed Madeline was wearing a ring on her wedding finger as they questioned whether Justin had popped the question.

A picture showed her sporting the jewellery as she cuddled up to Justin while enjoying a bowl of Udon noodles together at a restaurant in Japan.

But the bling appeared to be an emerald and diamond promise ring, and another photograph showed her wearing a different ring on the same finger as she posed for a selfie.

In August, Madeline also made a rare public post about Justin as she took to Instagram to mark his 52nd birthday.

She shared a series of romantic selfies of them both and gushed over her partner in the caption.

In one picture, Madeline flashed a huge smile as she sat on Justin's lap while he lovingly gazed at her.

Justin is considered Australia's hospitality king, with more than 80 venues and billions in assets with names like the Ivy, Queen Chow and Establishment under his purview as CEO of Merivale.

He is the only son of Merivale Group founder and nightclub mogul John Hemmes and Justin took over the business after his father's death in 2015.

Madeline is the younger sister of fellow Aussie model Simone Holtznagel, who welcomed her first child, a daughter called Gia, in March last year, with her now-ex-boyfriend Jono Castano.