Self-ruled Taiwan faces increasing pressures from China -- which claims the island as its territory and has not ruled out using force to bring it under Beijing's control.

Taiwan's air force held exercises Wednesday at a training centre in the southern city of Kaohsiung, focusing on underwater escape and parachute rescue.

As the simulator vessel spun upside down under the water, trainees dressed in orange overalls escaped from the cabin, holding their breath as they shimmied out one-by-one.

"The hardest part... I would say is the multi-crew cabin submerged under the water and all the members have to evacuate one by one through the only exit," said Lieutenant Shen Chia-xiang.

"I have to stay calm, save my oxygen and not to make myself panic," he said.

The crew also learned to disentangle themselves from parachute ropes after they landed in the water.

Lieutenant Ceng Yu-ting said the parachute escape training program made her the most nervous.

"When I was out there at the open water, seeing my teammates not performing up to standard, and was dragged out of the parachute, I did feel nervous watching it."

On a near-daily basis, Beijing flies warplanes and sends naval vessels around Taiwan -- a tactic Taipei calls "grey-zone harassment".

Such actions stop short of war but wear down Taiwan's military and enable Beijing to monitor its movements.

The island is a little over a month out from the presidential inauguration of Lai Ching-te, Taiwan's current vice president who China has called a "dangerous separatist".

On Wednesday, Taipei's defence ministry said 10 Chinese warplanes and seven naval ships had been detected around the island in the 24 hours ending at 6:00 am (2200 GMT Tuesday).

It also announced that a US P-8A patrol aircraft had transited north to south through the Taiwan Strait -- a sensitive 180-kilometre (110-mile) waterway that separates the island from China.

Beijing often reacts angrily to foreign warships or warplanes transiting through the strait -- which it also claims -- though Taiwan, as well as its key partner the United States, touts a commitment to uphold freedom of navigation in the hotspot region.