When most people think of exploring the sea they envision romantic adventures such as those of a Jules Verne or Jacques Costeau.

But in a House committee room last week, any such romantic notions were swept aside as members of Congress and lobbyists for mining consortiums dealt with the nitty gritty of how to carve up the mineral riches on the ocean floor in light of Third World demands that rich countries share the wealth.

Untold billions of dollars are at stake in the taking from the sea of potato-sized nodules that can be porcessed to produce nickel, copper cobalt and manganese.

Knowledge of that fact, plus a rising number of disputes over fishing rights, rights to oil, shipping lanes and other maritime issues led the United Nations to convene a conference some five years ago to try to work out the internationally sticky problem of who owns the sea and how to divide its spoils.The conference started with the principle that the sea is the "common heritage of mankind" and wealth should be shared.

Some progress has been made, but an eight week session of the Law of the Sea Conference ended in New York last week with chief U.S. negotiator Elliot L. Richardson saying that settlement of the question of seabed mining had suffered a setback and that the proposals offered were "fundamentally unacceptable" to the U.S.

Richardson said he was recommending to President Carter that the government review whether it is in its interest to continue such negotiations.

Richardson complained that a compromise text unveiled last week gave too much power to an international authority, put severe limits on growth of the mining and required private industry to make its mining know-how available to the U.N. before being granted mining rights.

In short, one source said, Third World countries, many of which have the same minerals on their lands, went too far in trying to protect their own interests and in making demands on the industrial world.

Without knowing what had happened at the conference, the House Merchant Marine and Fisheries Committee - spurred on by mining consortiums involving such corporate giants as Kennecott Copper. U.S. Steel, Tenneco and Lockheed - had already ignored State Department pleas to wait and see how the Law of the Sea conference cam out. It was drafting a bill in effect requiring U.S. taxpayers to protect the companies against losses they might incur as a result of any future treaty.

Eight members of the committee signed a letter to subcommittee Chairman John Breaux (D-La.) asking that he postpone subcommittee markup of the bill until the conference was over and Richardson had a chance to report.

One member, Rep.-Gerry Studds (D-Mass.), circulated a "Dear Colleague" letter in which he warned that the bill which provides "special government treatment to four of the largest and wealthiest corporations in the world" could have "serious international repercussions - as well as potentially expensive consequences for the American taxpayer."

But Breaux, backed by the committee chairman, John Murphy (D-N.Y.), insisted on going ahead.

Murphy defended the rush, saying, "The U.S. mining companies . . . are presently the only entitles with the expertise to mine the deep seabed minerals. If the legislation is not passed during this session of Congress, the U.S. will lose its technological lead to other countries."

Leigh S. Ratiner, lobbyist for Kennecott Copper Corp., said the companies had been asking for such legislation for the last seven years.

"They have now reached the point where they have each spent $30 to $50 million a piece, and are about to go into major sealed-up tests to equipment and processing plants," Ratiner said this would require investments of $50 million $150 million more, and that the companies want some assurance from the government that their investments, wouldn't be lost as a result of terms of some future treaty.

Ratiner himself has become a controversial figure in the by-play. He was ocean mining administrator in the Interior Department and chief U.S. negotiator on the deep seabed mining committee of the Law of the Sea conference until Jan. 24, when he resigned to take a job with kennecott.

In April Ratiner briefed House staff members on the legislation without being identified as a Kennecott lobbyist until one staffer asked.

Another staff aide said he suspects Ratiner used his contacts at the LOS to supply the House committee with inside information about what was going on during the negotiations and to spur them to act.

Ratiner, employed by the law firm of Dickstein, Shapiro and Morin, deries the charges vigorously. He said that the firm researched the law and that he is not violating any conflict of interest law by his activities. He said he has had no contact with the LOS in the last two months, and that the failure to disclose his Kennecott connection was the fault of the staff that issued the invitation to the briefing, not his.

Under the bill that came out of the subcommittee last week, the U.S. government would grant licenses to the firms to mine and would insure liability up to $350 millions per company for any losses caused by a future treaty.

Amendments passed by the subcommittee have somewhat softened the bill's impact. One amendment would require the consortia to pay a kind of insurance premium of 0.25 per cent to 0.75 per cent of the value of their investments.

Another amendment would require the companies to set up a sort of revenue-sharing fund into which they would pay about 2 per cent of the value of the processed minerals as a royalty to be distributed among the underdeveloped nations.

But Breaux said he intends to fight the escrow fund in full committee because "it would lock in concete the U.S. position and tie the hands of our negotiator."

Murphy has promised to get the bill out of the full committee before the Aug. 5 recess.