The Navy is trying to persuade the public to support its plan to purchase three submarines from China for Bt36 billion (S$1.4 billion).
Navy commander in chief Admiral Kraisorn Chansuwanit said on Thursday that Thailand's maritime interests were estimated at Bt24 trillion, so the submarine purchase would be a fraction of that.
"It's the best worth [Thailand would get] for the money," he said, adding that the submarines would serve as the country's maritime "fences" for the next 30 years.
Thailand has a maritime area of over 300,000 square miles covering the Gulf of Thailand and the Andaman Sea.
He also disputed a claim that the Gulf of Thailand is too shallow for a submarine. "That's not true. The Navy has carefully studied the geographical environment," he said.
Earlier, Deputy Premier and Defence Minister Prawit Wongsuwan postponed seeking Cabinet endorsement for the submarine purchase plan.
Prawit instructed the Navy to raise public awareness about the plan so that the public understood the need for the submarines.
That was why he had not yet submitted the purchase plan for Cabinet approval.
He said the Navy had not cancelled the purchase because it was part of the plan to improve the country's naval capability.
Kraisorn said he had assigned his deputy, Admiral Narongpol Na Bangchang, to inform the public and the media about the Navy's need to acquire submarines. A document would be issued about the worthiness of the submarines.