Americans traveling to China are being warned about the possibility of detention, electronic surveillance and restrictions that could keep them from returning home, with a travel expert sharing critical information for people to know before they go. 

The U.S. State Department issued an updated Level 2 "Exercise Increased Caution" advisory for mainland China this week, citing concerns about wrongful detention and restrictions on leaving the country.

Travelers are told to be aware that routine professional, academic and personal activities, which carry no risk in Western countries, could be treated as criminal offenses under China's broad security laws.

STATE DEPARTMENT ISSUES TRAVEL ADVISORY AS ARRESTS AND EXIT BANS HIT POPULAR DESTINATION

The advisory also raises concerns about private communications, warning Americans that emails, texts and social media activity could be monitored by Chinese authorities.

"Assume that China's security services can read your emails, texts and social media posts if you send them to or from China," the Oct. 19 advisory states.

The State Department said some people have been detained or deported over private messages considered critical of Chinese authorities, even when those messages were sent outside China.

The risks extend beyond electronic communications.

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The State Department elaborated on possible detention without justification.

"The U.S. Department of State has determined that Americans are at serious risk of wrongful detention by the Government of China," the advisory states.

Those detained could spend years behind bars with limited contact with family members or U.S. officials, according to the department.

Travelers could also face restrictions that prevent them from leaving the country, even if they have not been detained.

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Chinese authorities have used the "exit bans" during investigations and business or civil disputes. Exit bans have also affected relatives of people under investigation, including children, according to the advisory.

Some travelers may not know they're prohibited from leaving until they try to fly home.

"U.S. citizens might only become aware of an exit ban when they attempt to depart China," the State Department said.

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Some bans have lasted for years. Officials warn there may be no clear way to challenge them in court.

Americans who plan to visit China are advised to travel with a U.S. passport and valid Chinese visa, enroll in the Smart Traveler Enrollment Program and arrange regular check-ins with family members or an employer.

Fox News Digital reached out to the U.S. State Department for further comment.

"Be aware of your surroundings. Think before you take a picture," advised Bobby Laurie, a longtime travel expert and former flight attendant.

"This is one of those situations where maybe you were spotted taking pictures of law enforcement on the street, or you were somewhere you shouldn't have been. Maybe you were inadvertently near a protest on the streets," he added. 

"Then as your trip comes to an end, you head to the airport. You scan your boarding pass, ready to get through immigration to fly home. And then you realize you're actually not allowed to fly home. There has been an exit ban placed on you."

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He said anyone traveling to China should go with "a cell phone or electronic device that is really stripped down just to what you need for your trip."

Leave confidential information at home, he also urged. 

A 70-year-old man disappeared for more than 24 hours, prompting an extensive search that stretched into the evening.

The Oahu man was last seen in the Big Island's Volcano area before he was reported missing around 12:16 p.m. Oct. 19, according to the Hawaii Police Department.

The man was identified as David Arai, whose son told Hawaii-based news station KHON2 his father was familiar with the area's hiking trails and that he frequently hiked alone.

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Police believed the man was at risk due to his age and other information gathered during the investigation.

Officers later located Arai's empty rental car inside Hawaii Volcanoes National Park, according to the department.

Hawaii Island police and National Park personnel searched the area on the ground, while a Hawaii Fire Department helicopter assisted from above.

Fox News Digital reached out to the Hawaii Police Department and David Arai for comment.

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K-9 Trina, a 3-year-old Labrador retriever specially trained to track people by scent, joined the search with her handler, Officer Christopher Ross, police said.

At about 7:30 p.m., Trina located the man on a trail roughly 2 miles from where his rental car had been found, according to the department.

Ross told KHON2 that Arai was lying on his back in bushes just off the trail when they found him.

Trina approached the man and licked his hand, according to the officer.

"The man was safely carried back to the trailhead and was subsequently transported to Hilo Benioff Medical Center for medical treatment due to dehydration and exposure," the department said in the press release.

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The discovery marked the second time in two months that Trina located a missing person, according to police.

Originally from Sweden, Trina is trained to help locate missing children and endangered adults throughout Hawaii.

Just last month, she helped authorities locate an endangered teenager in Waikoloa, police said.

Fox News Digital previously reported on another search for an older hiker who disappeared during a trip in Northern California.

Mary Beth Granbery, 72, was reported missing after leaving for a multiday camping trip on Sept. 28 and failing to return as expected.

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Family members later found her camper van at the Cabin Creek Trailhead, prompting authorities in Siskiyou and Shasta counties to launch a coordinated search.

Ground crews found Granbery alive near Cabin Creek on Oct. 4 after she fell down a steep embankment and suffered serious injuries and exposure to the elements.

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A California Highway Patrol helicopter helped lift Granbery from the rugged terrain before she was taken to a hospital, where authorities said she was in stable condition with non-life-threatening injuries.

The national park is also home to Kilauea, which recently erupted for the 55th time since late 2024 after a rare two-month pause, according to Fox Weather.