Here are the main river- and water-based excursions you can do from Bentota (southern Sri Lanka), with typical durations, sights, price ranges and booking tips.

1. Madu Ganga (Madu River) boat safari — mangroves, islands, cinnamon island, temple, fish spa

• What it is: A slow motorboat ride through the mangrove channels of the Madu Ganga (near Balapitiya), with stops for Cinnamon Island, small island temples (e.g., Kothduwa), birdlife, and the optional fish‑spa/fish therapy. (Trawell.in)
• Typical duration: 1–2 hours (many operators offer 1‑hour “short” or ~2‑hour standard trips). (maduriversafari.com)
• Typical price: roughly USD 10–40 per person for group/shared boat rides; private boat hires or packages commonly run USD 25–100+ depending on length and inclusions. Organized excursions from Bentota often advertise prices in the USD ~30–80 range; larger “private & all‑inclusive” packages or combined day tours cost more. (TripAdvisor.com)
• Notes: Many providers include hotel pickup in the Bentota / Aluthgama / Ahungalla area. Fish‑spa and some island entrance fees are sometimes extra. (BentotaTravelMart.com)

2. Bentota River safari / Bentota lagoon excursions — birdlife, crocodiles, local life

• What it is: Shorter boat trips on the Bentota River and adjacent lagoons to see birds, monitor lizards, sometimes crocodiles, and local riverside villages. Good if you want something closer to Bentota town and shorter than the Madu River transfer. (BentotaTour.com)
• Typical duration: 1–2 hours.
• Typical price: group rates often start around USD 20–40 per person; private small-boat hires available for higher fixed prices. (TripAdvisor.com)

3. Combined half‑ or full‑day tours (Galle + river safari + turtles + stilt fishermen)

• What it is: Popular packaged day trips that combine a Madu/Bentota river safari with visits to Kosgoda turtle hatchery, Galle Fort, and the stilt fishermen (photo stop). These are convenient if you want multiple highlights in one day. (TripAdvisor.com)
• Typical duration: half day (4–5 hours) to full day (7–9+ hours).
• Typical price: packages commonly range USD ~70–140 per person depending on inclusions and transport origin. (TripAdvisor.com)

4. Kayaking / sunrise mangrove paddles on Madu Ganga

• What it is: Guided kayaking through mangroves (often offered as sunrise trips for birdlife and calm conditions). More active and gives closer access to channels than motorboats. (TripAdvisor.com)
• Typical duration & price: often 1.5–3 hours; prices vary (examples USD 110–150 for sunrise kayak from Bentota/Colombo when offered via organized tours). (TripAdvisor.com)

5. Lagoon fishing and local village tuk‑tuk safaris

• What it is: Hands‑on local experiences such as lagoon fishing trips (cast nets, line fishing) or guided tuk‑tuk village safaris around Bentota. Good for cultural interaction and trying local cuisine. (TripAdvisor.com)

Practical tips and recommendations

• Best time: Early morning or late afternoon for cooler temperatures and better wildlife/bird activity; avoid the hottest midday hours. Madu Ganga operators commonly run 6:00–18:00. (Trawell.in)
• Bookings: You can book through your hotel (common and convenient), local tour desks in Bentota, or online marketplaces (TripAdvisor/Viator/local operators). Compare whether pickup, entrance fees (e.g., temples, fish spa), and turtle hatchery donations are included. (BentotaTravelMart.com)
• Costs: Prices vary with season, private vs shared boat, and length. Expect shared/group boat trips to be the best value; private boats are recommended if you want flexibility or a small group experience. (Trawell.in)
• What to bring: sun protection, insect repellent, light rain jacket in rainy season, binoculars for birds, cash for small entrance fees/tips and souvenir cinnamon purchases. Many stops sell fresh cinnamon (a local specialty). (BentotaTravelMart.com)
• Safety & environment: Use licensed operators where possible, wear lifejackets if provided, and avoid feeding wildlife or leaving litter in mangroves.

If you’d like, I can:

• Find available tours on specific dates (I’ll check live availability and prices), or
• Compare 3 recommended operators with links and recent reviews (I can fetch TripAdvisor/official pages), or
• Build a half‑day vs full‑day sample itinerary from Bentota.

Which would you prefer?