Indian travelers with a valid ETA will be issued with a visa on arrival at Sri Lankan border control. They must simply show the following documents, which are requirements for all international visitors:
- Valid passport (registered to the ETA)
- Return or onward ticket
- Proof of sufficient funds to support yourself during your trip (e.g. a bank statement)
You may also be asked to show a copy of the ETA confirmation, so it is advisable to print it when you receive the email.
As long as this documentation is in order, you will be given a Sri Lankan visa on arrival and you will be able to enter the country immediately.
Passengers who are unable to get an ETA in advance will have to spend a long time a border control, first standing in line to get the visa application form, then dealing with the paperwork, and finally joining the normal queue to clear immigration.
This is why the ETA is regarded as being far more convenient and is the preferred option for most Indian travelers.