Princess Cruises' Pacific Princess will make a heart-stopping entry into Sydney this Saturday lighting up the Harbour with a giant, beating heart.

In honour of her namesake, the original Love Boat, Pacific Princess will wear her heart on her bow on Valentine's Day.

Believed to be the largest at sea, the 4.5m LED illuminated heart will form part of a love-filled salute as the 30,000-tonne ship and its 680-guests kickstart Sydney's Valentine's Day celebrations.

The Pacific Princess will be decked out in full romance regalia including 300 heart flags flying from her dressing line and a four-meter high red heart painted on her funnel, while guests will be waving heart flags from her top decks.

To mark the first time Pacific Princess has arrived in Sydney for Valentine's Day, the ship has been given special permission to play a ship horn rendition of the well-known Love Boat theme while it passes the Opera House.

The modern day Love Boat is expected to sail through the heads at approximately 6am, cruising past the Opera House and under the Harbour Bridge around 6.30am before docking at White Bay Cruise Terminal about 7am.

Harbour vantage points to see the loved-up Pacific Princess include Bradfield Park at Kirribilli, the Sydney Opera House, and Mrs. Macquarie’s Chair in the Botanic Gardens.

Pacific Princess will be visiting Sydney as part of her 111-night world voyage which departed Los Angeles on January 23, 2015.