By international convention, a superyacht is any private vessel more than 30 metres (98ft) in length. A few years ago, there were only a handful but today, there are thousands of them and, amazingly, demand is on the up.

After a few years, the owner of a 30-metre yacht wants 40 or 50 metres of yacht and, right now, there are not enough quality shipyards in the world to cope with the demand.

Every year, buyers and sellers congregate in Monaco, and this year was busier than ever. At the Monaco Yacht Show this past weekend in Monte Carlo, there was an estimated $4.5 billion worth of yachts on display, and none of the 98 craft on exhibit were under 100 ft. !

The Wealth Bulletin (a Dow Jones site) has come up with a list of the 10 most expensive streets in the world. The survey revealed that the prices for the top homes in the best locations appear to have decoupled from the gloom and doom being felt in the wider property market.

If you want to live in the best accommodation in these streets you will need to be a billionaire, or not far behind !

Avenue Princess Grace in Monaco has been named at the top with a price tag of $190,000 per square metre. It is followed by Hong Kong’s Severn Road with a price of $121,000 per square metre (sq mt) at second and New York City’s Fifth Avenue at third place ($80,000 per sq mt).

Here is the complete list, with some sample property prices as tallied by Wealth Bulletin:

The 118 WallyPower is one of the most eye-catching yachts in today’s luxury boating market, created by the Monaco-based Wally Yachts. It is narrow and angular in design with black glass housing.

It is 118 feet long and is capable of reaching speeds as fast as 60 knots (70 mph, 110 km/h).

It is capable of this feat due to three Vericor TF50 gas turbines generating 16,800 hp. The three gas turbines each drive a Rolls-Royce Kamewa water jet, two steerable outboard and a non-steering booster on centerline.

Prince Albert II, the ruler of Monaco, recently christened a new cruise ship named after himself, which will be the newest addition to the Silversea line and said to be the most luxurious expedition ship ever to sail.

A gutted expedition ship now completely redecorated and outfitted to suit the most wealthy of customers it is ready for the most rugged of adventures with the most luxurious of accommodations.

The 132-passenger Prince Albert II, which formerly sailed as the World Discoverer before Silversea bought it in September, sets sail on June 12 from London on an inaugural season of 10- to 22-day adventure cruises focusing on the polar regions.

The first 54-meter mega yacht by AMY, the joint venture founded in October 2005 by Cantieri Navali Lavagna and T.Mariotti/Genova with a view to building Admiral branded displacement yachts, will be launched next July.

A grand party will celebrate this event, an important achievement for AMY: the advancement from spectators in the world of mega-yachts to significant players of such ever-growing industry.

Designed by Luca Dini and planned by AMY, the Admiral flagship enters the international stage as a truly unique vessel. Since the very first stages of design and construction of its steel hull and light alloy superstructure new construction criteria, typical in ship construction yet innovative in yacht building, have been adopted: the results are excellent.

World renowned luxury yacht agents Fraser Yachts recently added the wonderful 46m (151′) S/Y Lulworth for sale. Built in 1920 but wonderfully restored in 2006 to her former glory, S/Y Lulworth is available for sale with an asking price of Euro 14,950,000 through Richard Earp of Fraser Yachts, Monaco.