Here are several quiet, eco-conscious places you can consider for a last-night (same‑day / overnight) stay near Colombo. I’ve included approximate distance/time from Colombo, a short note on their eco credentials or focus, and a citation so you can check availability and book right away.

1. Eco Villa – Dehiwala / Mount Lavinia (Colombo suburbs)

• Why: Small eco‑focused boutique property in the Colombo area that emphasizes recycling, energy efficiency and a rooftop garden — easy and quiet compared with city centre hotels.
• Travel: within Colombo / Mount Lavinia (10–30 minutes from central Colombo depending on traffic).
• Good for: Quiet last‑night stays close to the city/airport. (hidmc.com)

2. Residence by Uga Escapes — Colombo (Cinnamon Gardens / central Colombo)

• Why: Boutique luxury hotel with sustainability practices and focus on local sourcing/artisan décor; quieter than the big seafront properties while still centrally located.
• Travel: central Colombo (10–20 minutes from many central spots).
• Good for: Comfortable, quieter overnight stays with sustainable practices. (etichotels.com)

3. Galle Face Hotel — Colombo (seafront)

• Why: Iconic seafront hotel that has implemented energy & waste reduction initiatives and runs marine/clean‑up efforts; the rooms facing away from Galle Road can be fairly peaceful at night.
• Travel: central Colombo seafront.
• Good for: If you want a mix of heritage and sustainability with easy access to the oceanfront. (etichotels.com)

4. Jetwing Vil Uyana — near Sigiriya (eco‑lodge example; for a longer quiet retreat)

• Why: One of Sri Lanka’s best‑known eco‑resorts (wetland restoration, conservation focused). Not in Colombo — recommended only if you’re willing to travel ~3–4 hours for a very quiet, nature‑forward stay.
• Travel: ~3–4 hours from Colombo (Sigiriya area).
• Good for: If “quiet + strong eco credentials” is the priority and you can travel further. (en.wikipedia.org)

5. Dolphin Beach / Kalpitiya eco‑beach camps

• Why: Small community-built eco beach camps with low‑impact tents and community involvement; about 2–2.5 hours north of Colombo. Very quiet, especially out of peak season.
• Travel: ~2–2.5 hours from Colombo (Kalpitiya peninsula).
• Good for: Quiet seaside last‑night stays if you’re OK with a slightly longer transfer. (en.wikipedia.org)

Quick booking tips for last‑night stays

• Use major same‑day booking apps (Booking.com, Agoda, Hotels.com) or call the hotel directly — many boutique/eco places hold a few rooms for walk‑ins but last‑minute availability varies.
• Ask the hotel for a “quiet room” away from road/front desk and confirm their sustainability practices if that’s important to you.
• If you need to be near the airport (late/early flights), Negombo has quick‑transfer eco options and is ~30–45 minutes from Bandaranaike International Airport (search “eco hotels Negombo”). (thetimes.co.uk)

If you’d like, I can:

• Check same‑day availability and nightly rates now for any one or two of these choices (I can search live availability and show options), or
• Send direct phone numbers/booking links for the properties above.

Which would you prefer me to do?