The Hague: Four-time Olympic swimming champion Inge de Bruijn of the Netherlands retired on Monday."My career is over," De Bruijn said. "It can't get any better. I'm at the ceiling and see no more challenges. I'm 33 years old - in swimming that's a grandmother."She hadn't competed in any major events since the 2004 Athens Olympics, and completed her career with eight Olympic medals overall, and five world championships. She earned three golds at the 2000 Sydney Games in the 50-meter freestyle, 100 free and 100 butterfly, and a silver in the women's 4x100 free relay.In Athens, De Bruijn defended her 50 free title, won silver in the 100 free, and bronze in the 100 butterfly, and another bronze in the 4x100 free relay.She repeated all three of her individual victories in Sydney at the 2001 world championships, earning a second successive world female swimmer of the year award from Swimming World magazine.Since the Athens Games, De Bruijn has appeared regularly on Dutch television, including a turn in the Netherlands' version of Dancing with the Stars.Even so, she said it was tough to finally end her career."I kept postponing it because it is the most difficult decision I've ever had to make," she said. "Swimming has been my whole life."De Bruijn still holds the 50 free and 100 butterfly world records, both set in 2000 at Sydney.