Tumesafiri maili moja ya bahari bila ugonjwa wa bahari.

Tumesafiri can be analyzed as:

• tu- = we
• -me- = a perfect marker, often meaning have
• -safiri = travel

So tumesafiri means we have traveled or sometimes simply we traveled, depending on context.

One useful thing to notice is that the verb is kusafiri (to travel), and this verb keeps its -i ending in forms like tumesafiri.

In Swahili, the subject is usually shown on the verb itself. So tu- already tells you the subject is we.

That means Tumesafiri by itself already means we have traveled. You could add sisi for emphasis, but it is not necessary:

• Tumesafiri = We have traveled
• Sisi tumesafiri = We have traveled / We are the ones who have traveled

Not always exactly, but it is often close.

The marker -me- usually shows a completed action with present relevance. So tumesafiri is often translated as we have traveled. In some contexts, though, English may simply use we traveled.

So it is best to think of -me- as a perfect/completed-action marker rather than trying to match it to only one English tense every time.

Because moja has to agree with the noun class of maili.

Maili belongs to the N-class (class 9/10), and with that class, one is moja.

Compare:

• maili moja = one mile
• mtu mmoja = one person

So mmoja is not the right agreement form for maili.

Usually, no. Maili is one of those nouns that often keeps the same form in both singular and plural.

For example:

• maili moja = one mile
• maili mbili = two miles

So the number word tells you whether it is singular or plural.

Here ya is the associative link, often translated as of.

So maili moja ya bahari is literally something like one mile of the sea. In natural English, that is best understood as one nautical mile or one sea mile in this context.

The form ya is used because it agrees with maili, which is in the N-class.

Because the connecting word must agree with ugonjwa, not with bahari.

• ugonjwa belongs to noun class 3 in the singular
• the associative form for that class is wa

So:

• ugonjwa wa bahari = literally illness of the sea
• natural meaning: seasickness

This is a good example of how Swahili agreement changes depending on the noun class of the first noun in the phrase.

Bila means without.

So:

• bila ugonjwa wa bahari = without seasickness

In natural English, you might also translate the whole idea as without getting seasick. Swahili does not need to copy the English wording exactly; using the noun phrase after bila is perfectly normal.

Because it is doing two different jobs:

• in maili moja ya bahari, it helps describe the kind of mile
• in ugonjwa wa bahari, it is part of the expression meaning seasickness

So the repetition is not a mistake. It is just the same noun being used in two separate phrases.

Yes, but the meaning would be less specific.

• maili moja = one mile
• maili moja ya bahari = one nautical mile / one sea mile

So if you want to make it clear that it is a sea-related or nautical measure, the longer phrase is useful.

Yes. This order is natural:

• Tumesafiri = the verb
• maili moja ya bahari = distance
• bila ugonjwa wa bahari = an added phrase saying without seasickness

So the sentence structure is basically:

We-have-traveled + one nautical mile + without seasickness

That is a normal way to build the sentence in Swahili.