You need an ETA for Sri Lanka if you have a United States passport
Visa options for Sri Lanka (2)
Entries Double
Stay for 30 days
Use within 180 days
Purpose Tourism
Approved by Saturday 22 March 2025
Visa on arrival for a maximum of 30 days
Travellers need a visa to visit Sri Lanka for Business or Tourism. Travellers can get a visa on arrival in Sri Lanka at the port of entry of Bandaranaike International Airport.
This is not offered by sherpa°.
Apply on the government site.