Maroney first crossed the English Channel as a 15-year-old swimmer. She later established the world record for a two-way crossing of the English Channel by a female in 17 hours 15 minutes in 1991. She swam around 48 km (28.5 miles) Manhattan Island four times, winning the 1990 (7:00:27) and 1994 Manhattan Island Marathon Swims (7:08:10), and finishing 8th in 1999 (7:15:59) and 4th in 1989 (7:52:13).
At the age of 22, she completed a well-publicized 180 km (111.8-mile) swim from Cuba to the USA across the Florida Strait in 24 hours 31 minutes on 12 May 1997, aided by a shark cage covered in mesh in order to keep out the Portuguese man-o-war. She also completed a 38 hour 33 minute 197 km (122-mile) swim on 1 June 1998 from Cuba to Mexico. She also completed a 160 km (98 mile) 27-hour swim from Jamaica to Cuba on 15 September 1999.