if i put an object into the sea. a golf ball for example, would that raise the whole sea level. even if it was extreamly small?

A report in this week's New Scientist says that sea levels are rising by 4mm/yr in the Gulf of Thailand compared to 1.8mm/yr in the rest of the oceans. How can this be so?

If water could be pressurised, how low would the sea level be due to the pressurising weight of the overlying water?

I always watch National Geographic movies and question myself: if you put a camera on the back of a seal, a penguin or some other underwater animals, does the animal even notice it, and does it hurt the animal?

I've seen the animations of icy meteorites filling the primordial oceans with (presumably) pure water, but rocks are not naturally 'salty', in a potato crisp sense, and extracted salt is from dried-out deposits originally from seawater. And why Sodium Chloride in particular ? 

The Challenger Deep in the Mariana Trench is the deepest point in Earth's oceans. The bottom there is 10,924 meters (35,840 feet) below sea level and therefor at a pressure of nearly 2000bar.  Even if the bomb detonation was higher pressure than would a steam bubble be generated or would it remain as superheated water and just dissipate?  If a steam bubble was generated would the shear mass of water surrounding the detonation point condense it?

It was about 300 mm long. One shot shows it cut open. If it is a plant, it was not obvious which was the attached end.

Alright, another strange Jellyfish question. This occurred in Viareggio, again in Italy, durring the early summer of last year. I was swimming in the sea, in which at first I did not see a single jellyfish, when all at once I was swimming in what was something like two parts jellyfish to one part water, if you get my drift. I know that now sudden blooms of medusae in the Mediterranean have been becoming common, but here's where it gets a little weird: every last one of them were dead, and their tentacles missing. What could have caused this? At first the only explaination I could think up was that perhaps they die after breeding, and that their tentacles had been chewed off. Which, nonetheless, makes little sense to me. And seeing that a creature whose body is 97% water decays quite rapidly as it is, I wouldn't think that their tentacles just happened to rot away first. I supposed it's worth noting that, although varying in size, all of the dead jellyfish were of the same species. All other types of jellyfish I saw that day in the area were alive and intact. Any ideas?

I was in Isola d'Elba, an island off the coast of Tuscany, early last spring durring an enormous jellyfish bloom. At about mid-afternoon, before which the waters had been essentially clear of jellyfish, the area became completely swarmed all in about a period of twenty minutes. It consisted almost entirely of one species, which were obviously a type of comb jelly but whose description does not match anything I have been able to find on the net. They looked like Mnemiopsis, but were pinkish-orange in color (and relatively opaque), about twenty centimeters in length, and were covered in conicle, spike-like protrusions.

Among these were also a few individuals of a couple other species I have not been able to find information on. These include a type that was the exact size, color, and shape of a chicken egg, and another which was flat and resembled an elongated, outstretched pair of wings with a span of about 160 cm.

All of the species I have listed above were bioluminescent, emerged at the same time, dissolved easily to the touch, and did not sting (these being traits of jellyfish that live in the abyss, which therefore should not have been in shallow water to begin with). Unfortunately, I did not have a camera at the time and thusly can only describe them as best I can, but any information you might have on them would surely put my curiosity at ease.

As a young child, I used to love putting the shells like the ones in the picture, into my ear to listen to them. I remember being told that you hear the waves in them. I know that's not entirely true, but what exactly causes the sound we hear? And why don't we hear such sounds if we put other objects like it up to our ear?