Initially the core activity of the company was in the marine transportation and support services. Through perseverance and single-minded purpose in the pursuit of company objective, SESB managed to acquire and operate four Coastal Tankers, one Passenger Boat, two Tugs and Barges and one Cutter Suction Dredger within nine years of operation.

Currently the company employs a total of 96 people ranging from trained Fitters to Shipmasters on board of its vessels.

As part of its expansion and diversification programs, Sumai Engineering Sdn. Bhd. decided to venture into metal fabrication with emphasis on truck-mounted equipment such as Garbage compactors, Multi-Lifts, Trailers, Tankers and etc. As such activities require a much bigger space, the company decided to relocate this business sector and acquired a piece of land in Chendering Industrial Estate, about 6 km from Kuala Terengganu. This fabricationyard including the office which act as the headquarters for Sumai Group of Company had been commissioned in early 1993.

Sumai Engineering SESB had succesfully completed the "Laying of The Longest HDPE Pipeline in the world". This 27 kilometers pipe-line run across the South China Sea from Penarek in the mainland to Redang island, Tererngganu, Malaysia and was fully buried for the entire length.