The figures were announced Tuesday at the opening session of IAATO's 26th annual meeting in Rotterdam.
Overall, since the 2011/12 season, numbers have modestly increased, but are still considerably under the peak 46,265 reached during the 2007/08 austral summer.
Visiting the coastal regions of the Antarctic Peninsula on ships carrying fewer than 500 passengers remains the most popular form of tourism, IAATO said, accounting for 73% of visitors.
Some 26% of tourists did not set foot on Antarctica because they traveled on 'cruise-only' vessels that did not make landings.
The US contributed the most visitors, 34%, followed by Australia (11%), Britain (9%) and China and Germany (8% each).