Esther Tan

Esther Tan Cheng Yin (born 1975) is a Singaporean former naval diver and adventure racing athlete. She retired from the Republic of Singapore Navy in 2017, having held the rank of Major in the Naval Diving Unit. As Singapore's first female naval diver and an inductee of the Singapore Women's Hall of Fame, she has been called "Singapore's G.I. Jane".

Tan studied electrical and electronic engineering at Nanyang Technological University. She joined the Republic of Singapore Navy in 1995 and joined its Naval Diving Unit in 2000, becoming Singapore's first female naval diver. As a diver, she specialised in search-and-rescue missions and explosive ordnance disposal. The search-and-rescue operations in which Tan was involved included the recovery of missing sailors after the RSS Courageous collided with a container ship in 2003. She retired from the navy after 22 years of service in 2017, having held the rank of Major.

Tan started competing in adventure racing while she was a university student and has since taken part in dozens of international adventure races including marathons, triathlons and Ironman Triathlons. In 2016, she competed in the 700 km (430 mi) XPD Adventure Race in Tasmania, in which she slept for 29 hours over the 10-day race. In the 2007 Singapore Ironman 70.3 Triathlon, she was the top finishing Singaporean woman, and she was the only woman in the Asian team at the 2007 Adventure Racing World Series in Scotland, which covered 500 kilometres (310 mi). She was also in the overall champion team in the Ace Adventure Race and the Safra Adventure Race in 2007. In 2008, she finished first in the Women's Open of the Ironman 70.3 event in the Desaru Pengerang International Long Distance Triathlon.

Tan climbed Mount Everest in 2011; she did not summit, turning back 100 metres (330 ft) before the summit due to bad weather.

Tan was inducted into the Singapore Women's Hall of Fame in 2014. She was named a Her World Young Woman Achiever in 2006 and one of The Singapore Women's Weekly's "Great Women of Our Time" in 2017.