The 23-year-old woman was hit by the stressed animal’s trunk at the Koh Yao Elephant Care centre in Phang Nga province, according to police.
"A female tourist was killed while bathing an elephant," local police chief Jaran Bangprasert told AFP.
The authorities have contacted the Spanish Embassy to confirm the victim’s identity.
The sanctuary declined to provide details of the incident when contacted by AFP.
Wild elephants have killed 227 people, including tourists, in the past 12 years, according to the Department of National Parks, Wildlife and Plant Conservation.
An elephant killed a 49-year-old woman at a national park in Loei province, northern Thailand, in December 2024.
While encounters between villagers and wild elephants are common, attacks at sanctuaries remain rare.
Bathing elephants is a popular activity among visitors in Thailand, where about 2,800 elephants are held for tourism purposes across the country, according to World Animal Protection.
However, animal rights groups argue that bathing elephants can cause them distress, and some sanctuaries in the country do not allow it.