Is the passage describing an approximation of pi or is it one of the miracles of Bais Hamikdash?

In Sepher M'lakhim we read how different measurement was taken. I wonder if this passage (Ⅰ M'lakhim 7:23) is describing an approximation of PI (3.1415...), or was this one of the hidden miracles?

וַיַּעַשׂ אֶת־הַיָּם מוּצָק עֶשֶׂר בָּאַמָּה מִשְּׂפָתֹו עַד־שְׂפָתֹו עָגֹל ׀ סָבִיב וְחָמֵשׁ בָּאַמָּה קֹומָתֹו [וּקְוֵה כ] (וְקָו ק) שְׁלֹשִׁים בָּאַמָּה יָסֹב אֹתֹו סָבִיב׃

Now he made the sea of cast metal ten cubits from brim to brim, circular in form, and its height was five cubits, and thirty cubits in circumference.

Answer

It's approximating π, as is clear from the g'mara (Eruvin 14:1).

The problem is that that g'mara seems to be saying that it's a pretty precise approximation, and we know it's not. (Tosafos there raise this question and offer no answer.)

But to answer your question, whether it's an approximation of π or a miracle, it's the former.