The tsunami at Goa (west coast of India) and Kavaratti Island (Lakshadweep archipelago) in the Arabian Sea, caused by the 12 September 2007 Sumatra earthquake, was reported from cellular-based sea-level gauges in real-time on the Internet designed and established by the National Institute of Oceanography, Goa, India. The tsunami arrived at Kavaratti Island and Goa after traveling nearly 5 h : 15 min and 8 h respectively, from the source region in Sunda trench. The maximum trough-to-crest wave height at Kavaratti and Goa was approx. 5 and 29 cm respectively, and the dominant period was about 43 min. Arrival of a detectable tsunami signal first at Kavaratti Island and 2 h : 45 min later at the shallower Goa coastal region (Verem jetty) of the mainland indicates the importance of having highsensitivity real-time monitoring and Internet-accessible sea-level stations on India’s island locations for effective tsunami-warning purposes for the mainland.