From Bentota taxi to Diyawanna Oya airport then fly to Colombo airport. 1 h 11 min $154. From Aluthgama train to Colombo Fort, walk to Colombo Bastian Mawatha Bus Terminal, then line 187 bus to Katunayake Airport Bus Station. 2 h 49 min $2. From Bentota taxi to Colombo Airport (CMB). 1 h 21 min $64. From Bentota drive to Colombo Airport (CMB). 1 h 21 min $9.
Sri Lanka Railways operates a train from Bentota to Colombo Airport (CMB) every 3 hours. Tickets cost $1 - $2 and the journey takes 1 h 46 min. Sri Lanka Transport Board - SLTB ICT also services this route every 15 minutes.