DIARY: JOHAH AND THE WHALE-CHASERS !

The BBC's Jonah Fisher is on a Greenpeace ship tracking the Japanese whaling fleet in the Southern Ocean. You can follow his travels for the next two months on the Ten O'clock News, and in this diary.

FRIDAY 21 DECEMBER: JAPAN'S U-TURN
There are lots of smiles on the Esperanza this evening.
News that humpbacks are being taken off this year's Japanese whale hunt had been rumoured for a few days but confirmation came just as the sun was setting.

Guide to the Humpback
Japan's point of view
I'm not sure if someone on board was privy to inside information but a party had already been planned for the helicopter hangar at the back of the ship.
I am told it went well. Unfortunately, the huge interest in this story meant drinking beer was the last thing on my mind. It was more a question of working out which combination of tea, coffee and gingernut biscuits would keep me standing the longest.
The prevailing opinion on the ship is that the decision had come as a result of Australian pressure.

Map: Voyage to Antarctic waters

This week it was announced that Canberra would be sending a customs ship to the Antarctic waters to photograph and film the whalers, with a view to possibly taking Japan to court.
With the Australians an important trading partner, it seems Tokyo was unwilling to allow things to slip too far.
For Greenpeace, no sooner had the news come out than it was playing down its significance.
Fan base From the campaign room at the top of the ship, it was being stressed that this was just 50 of almost 1,000 whales which would still be killed.
Some 935 minke are on the list and 50 fin whales.
The fins are considered an endangered species but, unluckily for them, they do not have the same sort of fan base as the humpbacks.
So, the Esperanza continues on its steady journey south.
Friday was the smoothest day so far with beautiful crisp clear skies and albatrosses looping round behind the ship.
On Saturday, the ship goes into port for the last time.
A two-hour pit stop in Bluff, on the southernmost tip of New Zealand, will ensure that the Esperanza's fuel tanks are full to the brim so that she can last even longer at sea.

THURSDAY 20 DECEMBER: OFF TO THE SOUTH

At 0400 local time, water came racing through the rusty porthole on to the cabin floor.
After 10 days waiting for the Greenpeace ship - the Esperanza - to leave port in Auckland, my first night at sea was useful preparation for the tough conditions that lie ahead.

The Japanese fleet will be trying to lose the boats following it
Luckily for me, my two room-mates quickly leapt out of their bunks and fastened the porthole shut before another wave crashed through its circular pane of glass.
Our cabin is at the very front of the Esperanza which means we hear and feel every contact between the ship's bows and the waves outside.
Technical problems with the Greenpeace helicopter delayed the ship's departure from New Zealand.
Glum faces
The chopper is a vital part of this anti-whaling operation. Firstly, to locate the Japanese whaling fleet, and then to provide aerial video footage of the whalers' in action.

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Greenpeace knows only too well that there is little point making its protest in the isolation of Antarctic waters if it does not have graphic television footage of its actions to quickly send around the world.
So there were glum faces in the Esperanza's mess when news of the ship's departure from Auckland was posted on the communal chalkboard.
"NO HELI" was scrawled underneath it - crucial parts needed for the maintenance of the helicopter had not arrived in time, so the decision was taken to leave without it.
For the Greenpeace cameraman and the three-person German documentary crew - planning to film spectacular shots of icebergs and whalers from the air - it was particularly bad news.
Vulnerable
The Esperanza is not the only ship heading to the Antarctic waters.
Sea Shepherd, a marine conservation group, has already made it to the ice with its ship, named after the late Steve Irwin.
But it has been forced to go north again to Australia for repairs to one of its engines.
The Australian government has also got plans to send a ship to monitor the whalers' activities.
The Japanese have been whaling under government-issued scientific permits since the moratorium on commercial whaling was introduced in 1986.
But the number of whales killed has steadily risen from about 200 to more than 1,000 planned for this season.
This year, for the first time, 50 Humpback whales are included.
They are not just a favourite with whale-watchers, but population levels are considered to be vulnerable worldwide.
For the next two months, I'll be reporting for BBC News from the Esperanza as it journeys south down to the ice and searches for the Japanese whalers.
Hide-and-seek
It is no free ride. We are paying our way and, of course, I have absolute editorial independence to say what I want without fear of being taken off air or thrown overboard.

I'll have sea-sickness pills to hand in the infamous Southern Ocean
Once we reach the Antarctic ice, an elaborate game of hide-and-seek between whalers and environmentalists will begin.
If the Japanese prove better at hiding than the Greenpeace crew are at seeking, it is very possible that I may see very little and this web diary will turn into long discussions about the relative merits of passing icebergs and penguins.
I am still not sure whether or not sending me on this trip is a big in-joke by BBC editors back in London.
I am certain that a colleague was only looking for a quick laugh (and found it) when they first suggested that they send a Jonah down to cover this whale story.

But, as the chuckles died away, the idea stuck and here I am preparing to cross the infamous Southern Ocean - sea-sickness pills firmly in hand.

BBC NEWS REPORT.