Hello my friend,and thank you so much for the reply.Ikelite doesn't have a port for 14-24,only Subal has one and it costs 1400 euro (only the port...) Moreover ikelite has a port for tamron 28-75.Do you think I will be fine with Tamron or I should get a Nikon 16mm or Sigma 15mm?
Generally ikelites housings are fine right?
Ok magic filters will be needed...
A last question,is there any difference between ikelites port that costs about 150e (usable for one lens) and the dome which is for a group of similar lens and costs about 300e?
I read something about lack of focus with the ports only.Is that true or I misunderstood?
Sorry for my English...Thank you.
Ikelite are fine product, the design is different than the aluminum housing and ergonomic are somewhat different, but price wise they do have a an edge, they are sometime snobed by photographer, but overall they are reliable housings. In the end, between the housing you would wish you could have and the one you actually could afford, well its better to be underwater shooting than dreaming about it 
The 8" dome port from Ikelite should work well with the Tamron, you might consider adding a +2 close up lens to improve close focusing, about the port, I am not that familiar with the Ikelite system as such, but I would think that the modular port system would pay off in the long run, in other word, paying more now will save you money later, a fisheye is a definitive plus underwater, I would go with the Sigma 15mm, it a better lens than the now very tired and obsolete Nikon 16mm which has not changed since the day of film cameras.
Many if not most lens/port set up for underwater will not let you have access to manual focus if the lens is a zoom, this is probably where aluminum (more expensive) housing will make the difference, I know Subal (as well as us) do offer an extension ring with an extra focusing knob for certain lens (mostly for Canon lenses as they are the one used more often for pro video footage). with the D700, getting a good quality focus light (I know, more money to spend still!!!
) will make all the difference.
Cheers.
BTW, nothing wrong with your english my friend!