Vijeesh runs canoe tours which are an excellent way to explore Munroe Island. You get to go places that the house boats can't and will literally be going through the village and get to see life there. He has great English and an excellent personality. Also runs a home stay on the island. Rickshaw ~₹400 from Kollam or local train, contact him via email/phone for train details.
Malayalam: ഇൻഫന്റ് ജീസസ് കത്തീഡ്രൽ, Portuguese: Igreja do Bom Jesú
A vestige of the Portuguese rule of Kollam, established in 1614.
Thangassery Fort
Some limited standing ruins of an old colonial fort. You can see two different sides of the building, the first from the harbour side (where it is visible at some distance), and the second from the opposite side. The site is slightly overgrown so beware of snakes if you venture close. An auto-rickshaw from the Main Road bus stop cost ₹50.
A modern lighthouse in a historic Christian quarter that is possible to climb in the afternoons. Best to combine with the Thangassery Fort, as the two sites are in easy and shaded walking distance.