From Cambodia: Nong Nok Khiene – Trapeang Kriel

Overview

The Nong Nok Khiene (Laos) – Trapeang Kriel (Cambodia) crossing sits on Route 13, about 60 km from Stung Treng, about 30 km from Nakasang (the pier for Don Det / Don Khon) and about 150 km from Pakse.

Typical routes

Phnom Penh / Siem Reap → Stung Treng → border → Nakasang / Don Det — combined bus/van + boat tickets are sold in Cambodia's main towns.
Stung Treng → Pakse — some companies run through, around 4–5 hours including the border.
You usually change vehicles at the border or in Nakasang — make sure your ticket covers your final destination.

At the border

Stamp out of Cambodia, then walk to the Lao side.
Get a visa on arrival or show your e-Visa (check whether this crossing accepts e-Visas when you travel).
Sample opening hours about 07:00–17:00 (sample data — please verify).

Unofficial fees

Small "stamping" or "health check" fees (a few dollars) have been reported on both sides in the past. Stay polite and calm and ask for a receipt — legitimate overtime fees should come with one.

Onward from the border

To the 4,000 Islands: get off at the Ban Nakasang junction and take a boat to Don Det / Don Khon (sample 25,000–30,000 LAK per person).
To Pakse: van or songthaew from Nakasang, about 2.5–3 hours (sample 60,000–80,000 LAK per person).

Tips

Bring small, clean US dollar notes — there are no ATMs at the border.
Leave early so you make the last boats from Nakasang.
Buy from companies with a real office and keep your ticket until you arrive.

Information is sample data — please check the official Lao immigration sources before travelling.