Then again, there may be compelling evidence that undersea volcanic activity is playing a significant role.

In hot water: world sets ocean temperature record
[link to news.yahoo.com]

key quote:
Breaking heat records in water is more ominous as a sign of global warming than breaking temperature marks on land, because water takes longer to heat up and does not cool off as easily as land.
"This warm water we're seeing doesn't just disappear next year; it'll be around for a long time," said climate scientist Andrew Weaver of the University of Victoria in British Columbia. It takes five times more energy to warm water than land.
The warmer water "affects weather on the land," Weaver said. "This is another yet really important indicator of the change that's occurring."
Georgia Institute of Technology atmospheric science professor Judith Curry said water is warming in more places than usual, something that has not been seen in more than 50 years.
Add to that an unusual weather pattern this summer where the warmest temperatures seem to be just over oceans, while slightly cooler air is concentrated over land, said Deke Arndt, head of climate monitoring at the climate data center.
The pattern is so unusual that he suggested meteorologists may want to study that pattern to see what's behind it.

when queried about the proposed theory that undersea volcanic activity is causing this heating, someone wrote:

the worlds oceans cover an area of 361 million square kilmometer with an average depth of 3.5 km. This would give a volume in the order of 1263 million CUBIC kilometers.

A calorie as the amount of energy required to raise one gram one kelvin.

The mass of the oceans is c. 1.4 × 1021 kilograms or 1.4*10^24 grams. That would roughly require 1.4*10^24 calories to raise the temperature one degree.
Q =mc delta T
or heat energy = mass times specific heat capactity times change in temperature.
Specific heat capacity of stone is 0.2. The temperature of molten rock can very generously be given as 2000C.
1.24^24calories = m * 0.2 * 2000 C.
1.24/400 =m
3.1* 10^20grams = m
3.1*10^14 tonnes of molten rock would be required.
Basalt is 3011 kg cubic meter
So we would be looking at 1 *10^14 cubic meters of rock ADDITIONAL volcanic activity (not just regular background activity).
[1 *10^8 cubic kilometers. So that would be 1*10^8 square kilometers of rock one kilometer high.]
We are talking continent formation, not a bit of volcanic activity!!!!!!!!!!!!!!!!!!!

Incidently I did this at work on lunch so any holes in the maths feel free to jump in and point them out.

food for thought....